diff options
| -rw-r--r-- | ChangeLog | 13 | ||||
| -rw-r--r-- | NEWS | 8 | ||||
| -rw-r--r-- | awk.h | 9 | ||||
| -rw-r--r-- | awklib/eg/test-programs/gen-float-table.awk | 59 | ||||
| -rw-r--r-- | awklib/eg/test-programs/gen-float-table.c | 60 | ||||
| -rw-r--r-- | awklib/eg/test-programs/gen-float-table.py | 42 | ||||
| -rw-r--r-- | builtin.c | 2 | ||||
| -rw-r--r-- | doc/ChangeLog | 27 | ||||
| -rw-r--r-- | doc/gawk.info | 1284 | ||||
| -rw-r--r-- | doc/gawk.texi | 273 | ||||
| -rw-r--r-- | doc/gawktexi.in | 273 | ||||
| -rw-r--r-- | doc/it/ChangeLog | 4 | ||||
| -rwxr-xr-x[-rw-r--r--] | doc/it/gawktexi.in | 308 | ||||
| -rw-r--r-- | doc/wordlist | 2 | ||||
| -rw-r--r-- | eval.c | 96 | ||||
| -rw-r--r-- | interpret.h | 12 | ||||
| -rw-r--r-- | mpfr.c | 44 | ||||
| -rw-r--r-- | node.c | 3 |
18 files changed, 1802 insertions, 717 deletions
@@ -106,6 +106,19 @@ 2020-11-02 Arnold D. Robbins <arnold@skeeve.com> + Make gawk numeric comparisons act like C doubles. + MPFR differs from doubles w.r.t. NaN, not sure why yet. + + * awk.h (scalar_cmp_t): New enum. + * builtin.c (format_nan_inf): Use mpfr_signbit, not mpfr_sgn. + * eval.c (cmp_doubles): New routine. + (cmp_scalars): Change type to bool, rework logic. + * interpret.h (r_interpret): Rework scalar comparisons. + * mpfr.c (mpg_cmp_as_numbers): New routine. + * node.c: Use <math.h>, not "math.h", minor comment edits. + +2020-11-02 Arnold D. Robbins <arnold@skeeve.com> + * re.c (make_regexp): Cast len parameter to int to avoid compiler warnings. @@ -4,6 +4,14 @@ are permitted in any medium without royalty provided the copyright notice and this notice are preserved. +Changes from 5.1.x to 5.2.0 +--------------------------- + +1. Numeric scalars now compare in the same way as C for the relational +operators. Comparison order for sorting has not changed. This only +makes a difference when comparing Infinity and NaN values with +regular numbers; it should not be noticeable most of the time. + Changes from 5.1.0 to 5.1.1 --------------------------- @@ -1576,6 +1576,15 @@ typedef enum { extern field_sep_type current_field_sep(void); extern const char *current_field_sep_str(void); +typedef enum { + SCALAR_EQ, + SCALAR_NEQ, + SCALAR_LT, + SCALAR_LE, + SCALAR_GT, + SCALAR_GE, +} scalar_cmp_t; + /* gawkapi.c: */ extern gawk_api_t api_impl; extern void init_ext_api(void); diff --git a/awklib/eg/test-programs/gen-float-table.awk b/awklib/eg/test-programs/gen-float-table.awk new file mode 100644 index 00000000..c35f2dff --- /dev/null +++ b/awklib/eg/test-programs/gen-float-table.awk @@ -0,0 +1,59 @@ +function eq(left, right) +{ + return left == right +} + +function ne(left, right) +{ + return left != right +} + +function lt(left, right) +{ + return left < right +} + +function le(left, right) +{ + return left <= right +} + +function gt(left, right) +{ + return left > right +} + +function ge(left, right) +{ + return left >= right +} + +BEGIN { + nan = sqrt(-1) + inf = -log(0) + split("== != < <= > >=", names) + names[3] = names[3] " " + names[5] = names[5] " " + split("eq ne lt le gt ge", funcs) + + compare[1] = 2.0 + compare[2] = values[1] = -sqrt(-1.0) # nan + compare[3] = values[2] = sqrt(-1.0) # -nan + compare[4] = values[3] = -log(0.0) # inf + compare[5] = values[4] = log(0.0) # -inf + + for (i = 1; i in values; i++) { + for (j = 1; j in compare; j++) { + for (k = 1; k in names; k++) { + the_func = funcs[k] + printf("%g %s %g -> %s\n", + values[i], + names[k], + compare[j], + the_func(values[i], compare[j]) ? + "true" : "false"); + } + printf("\n"); + } + } +} diff --git a/awklib/eg/test-programs/gen-float-table.c b/awklib/eg/test-programs/gen-float-table.c new file mode 100644 index 00000000..ae1d5dd4 --- /dev/null +++ b/awklib/eg/test-programs/gen-float-table.c @@ -0,0 +1,60 @@ +#include <stdio.h> +#include <math.h> +#include <stdbool.h> + +#define def_func(name, op) \ + bool name(double left, double right) { \ + return left op right; \ + } + +def_func(eq, ==) +def_func(ne, !=) +def_func(lt, <) +def_func(le, <=) +def_func(gt, >) +def_func(ge, >=) + +struct { + const char *name; + bool (*func)(double left, double right); +} functions[] = { + { "==", eq }, + { "!=", ne }, + { "< ", lt }, + { "<=", le }, + { "> ", gt }, + { ">=", ge }, + { 0, 0 } +}; + +int main() +{ + double values[] = { + -sqrt(-1), // nan + sqrt(-1), // -nan + -log(0.0), // inf + log(0.0) // -inf + }; + double compare[] = { 2.0, + -sqrt(-1), // nan + sqrt(-1), // -nan + -log(0.0), // inf + log(0.0) // -inf + }; + + int i, j, k; + + for (i = 0; i < 4; i++) { + for (j = 0; j < 5; j++) { + for (k = 0; functions[k].name != NULL; k++) { + printf("%g %s %g -> %s\n", values[i], + functions[k].name, + compare[j], + functions[k].func(values[i], compare[j]) ? "true" : "false"); + } + printf("\n"); + } + } + + return 0; +} diff --git a/awklib/eg/test-programs/gen-float-table.py b/awklib/eg/test-programs/gen-float-table.py new file mode 100644 index 00000000..8631b817 --- /dev/null +++ b/awklib/eg/test-programs/gen-float-table.py @@ -0,0 +1,42 @@ +from math import * + +nan = float('NaN') +inf = float('Inf') + +def eq(left, right): + return left == right + +def ne(left, right): + return left != right + +def lt(left, right): + return left < right + +def le(left, right): + return left <= right + +def gt(left, right): + return left > right + +def ge(left, right): + return left >= right + +func_map = { + "==": eq, + "!=": ne, + "< ": lt, + "<=": le, + "> ": gt, + ">=": ge, +} + +compare = [2.0, nan, -nan, inf, -inf] +values = [nan, -nan, inf, -inf] + +for i in range(len(values)): + for j in range(len(compare)): + for op in func_map: + print("%g %s %g -> %s" % + (values[i], op, compare[j], func_map[op](values[i], compare[j]))) + + print("") @@ -4277,7 +4277,7 @@ format_nan_inf(NODE *n, char format) goto fmt; } else if (mpfr_inf_p(n->mpg_numbr)) { - strcpy(buf, mpfr_sgn(n->mpg_numbr) < 0 ? "-inf" : "+inf"); + strcpy(buf, mpfr_signbit(n->mpg_numbr) ? "-inf" : "+inf"); goto fmt; } else diff --git a/doc/ChangeLog b/doc/ChangeLog index f595e245..8e94b98e 100644 --- a/doc/ChangeLog +++ b/doc/ChangeLog @@ -62,12 +62,39 @@ * gawkworkflow.texi: Add an additional web resource. * gawktexi.in: More edits in sample programs chapter. +2020-11-20 Arnold D. Robbins <arnold@skeeve.com> + + * gawktexi.in (Strange values): Correct the description of what + happens with infinity. Thanks to Antonio Columbo for pointing + out the problem. + 2020-11-16 Arnold D. Robbins <arnold@skeeve.com> * gawktexi.in (Nextfile Statement): Clarify what happens in a BEGINFILE rule. * gawktexi.in: Additional small fixes. +2020-11-15 Arnold D. Robbins <arnold@skeeve.com> + + * gawktexi.in (Strange values): Add test programs inside + @ignore; extracted to example directory. + +2020-11-09 Arnold D. Robbins <arnold@skeeve.com> + + * gawktexi.in: Samll improvement in strange numbers section. + +2020-11-04 Arnold D. Robbins <arnold@skeeve.com> + + * gawktexi.in (Strange values): New section on NaN and infinity. + Update some other bits to point to it. + * wordlist: Updated with more words. + +2020-11-16 Arnold D. Robbins <arnold@skeeve.com> + + * gawktexi.in (Nextfile Statement): Clarify what happens in + a BEGINFILE rule. +>>>>>>> master + 2020-10-31 Arnold D. Robbins <arnold@skeeve.com> * texinfo.tex: Updated from GNULIB. diff --git a/doc/gawk.info b/doc/gawk.info index 955c89ce..12b712c6 100644 --- a/doc/gawk.info +++ b/doc/gawk.info @@ -547,6 +547,7 @@ in (a) below. A copy of the license is included in the section entitled * Inexact representation:: Numbers are not exactly represented. * Comparing FP Values:: How to compare floating point values. * Errors accumulate:: Errors get bigger as they go. +* Strange values:: A few words about infinities and NaNs. * Getting Accuracy:: Getting more accuracy takes some work. * Try To Round:: Add digits and round. * Setting precision:: How to set the precision. @@ -6933,8 +6934,8 @@ width. Here is a list of the format-control letters: On systems supporting IEEE 754 floating-point format, values representing negative infinity are formatted as '-inf' or '-infinity', and positive infinity as 'inf' or 'infinity'. The - special "not a number" value formats as '-nan' or 'nan' (*note Math - Definitions::). + special "not a number" value formats as '-nan' or 'nan' (*note + Strange values::). '%F' Like '%f', but the infinity and "not a number" values are spelled @@ -12826,7 +12827,7 @@ brackets ([ ]): 'log(X)' Return the natural logarithm of X, if X is positive; otherwise, - return 'NaN' ("not a number") on IEEE 754 systems. Additionally, + return NaN ("not a number") on IEEE 754 systems. Additionally, 'gawk' prints a warning message when 'x' is negative. 'rand()' @@ -24209,18 +24210,10 @@ material here: another number and infinity produce infinity. "NaN" - "Not a number."(1) A special value that results from attempting a - calculation that has no answer as a real number. In such a case, - programs can either receive a floating-point exception, or get - 'NaN' back as the result. The IEEE 754 standard recommends that - systems return 'NaN'. Some examples: - - 'sqrt(-1)' - This makes sense in the range of complex numbers, but not in - the range of real numbers, so the result is 'NaN'. - - 'log(-8)' - -8 is out of the domain of 'log()', so the result is 'NaN'. + "Not a number." A special value that results from attempting a + calculation that has no answer as a real number. *Note Strange + values::, for more information about infinity and not-a-number + values. "Normalized" How the significand (see later in this list) is usually stored. @@ -24279,11 +24272,6 @@ Table 16.3: Basic IEEE format values NOTE: The precision numbers include the implied leading one that gives them one extra bit of significand. - ---------- Footnotes ---------- - - (1) Thanks to Michael Brennan for this description, which we have -paraphrased, and for the examples. - File: gawk.info, Node: MPFR features, Next: FP Math Caution, Prev: Math Definitions, Up: Arbitrary Precision Arithmetic @@ -24376,6 +24364,7 @@ be sure of the number of significant decimal places in the final result. * Inexact representation:: Numbers are not exactly represented. * Comparing FP Values:: How to compare floating point values. * Errors accumulate:: Errors get bigger as they go. +* Strange values:: A few words about infinities and NaNs. File: gawk.info, Node: Inexact representation, Next: Comparing FP Values, Up: Inexactness of computations @@ -24440,7 +24429,7 @@ values with a delta, you should be sure to use 'difference < abs(delta)' in case someone passes in a negative delta value. -File: gawk.info, Node: Errors accumulate, Prev: Comparing FP Values, Up: Inexactness of computations +File: gawk.info, Node: Errors accumulate, Next: Strange values, Prev: Comparing FP Values, Up: Inexactness of computations 16.4.1.3 Errors Accumulate .......................... @@ -24488,6 +24477,64 @@ representations yield an unexpected result: -| 4 +File: gawk.info, Node: Strange values, Prev: Errors accumulate, Up: Inexactness of computations + +16.4.1.4 Floating Point Values They Didn't Talk About In School +............................................................... + +Both IEEE 754 floating-point hardware, and MPFR, support two kinds of +values that you probably didn't learn about in school. The first is +"infinity", a special value, that can be either negative or positive, +and which is either smaller than any other value (negative infinity), or +larger than any other value (positive infinity). When such values are +generated, 'gawk' prints them as either '-inf' or '+inf', respectively. +It accepts those strings as data input and converts them to the proper +floating-point values internally. + + Infinity values of the same sign compare as equal to each other. +Otherwise, operations (addition, subtraction, etc.) involving another +number and infinity produce mathematically reasonable results. + + The second kind of value is "not a number", or NaN for short.(1) +This is a special value that results from attempting a calculation that +has no answer as a real number. In such a case, programs can either +receive a floating-point exception, or get NaN back as the result. The +IEEE 754 standard recommends that systems return NaN. Some examples: + +'sqrt(-1)' + This makes sense in the range of complex numbers, but not in the + range of real numbers, so the result is NaN. + +'log(-8)' + -8 is out of the domain of 'log()', so the result is NaN. + + NaN values are strange. In particular, they cannot be compared with +other floating point values; any such comparison, except for "is not +equal to", returns false. NaN values are so much unequal to other +values that even comparing two identical NaN values with '!=' returns +true! + + NaN values can also be signed, although it depends upon the +implementation as to which sign you get for any operation that returns a +NaN. For example, on some systems, 'sqrt(-1)' returns a negative NaN. On +others, it returns a positive NaN. + + When such values are generated, 'gawk' prints them as either '-nan' +or '+nan', respectively. Here too, 'gawk' accepts those strings as data +input and converts them to the proper floating-point values internally. + + If you want to dive more deeply into this topic, you can find test +programs in C, 'awk' and Python in the directory +'awklib/eg/test-programs' in the 'gawk' distribution. These programs +enable comparison among programming languages as to how they handle NaN +and infinity values. + + ---------- Footnotes ---------- + + (1) Thanks to Michael Brennan for this description, which we have +paraphrased, and for the examples. + + File: gawk.info, Node: Getting Accuracy, Next: Try To Round, Prev: Inexactness of computations, Up: FP Math Caution 16.4.2 Getting the Accuracy You Need @@ -38024,603 +38071,604 @@ Index Tag Table: Node: Top1200 -Node: Foreword344559 -Node: Foreword449001 -Node: Preface50533 -Ref: Preface-Footnote-153392 -Ref: Preface-Footnote-253501 -Ref: Preface-Footnote-353735 -Node: History53877 -Node: Names56229 -Ref: Names-Footnote-157333 -Node: This Manual57480 -Ref: This Manual-Footnote-164119 -Node: Conventions64219 -Node: Manual History66588 -Ref: Manual History-Footnote-169585 -Ref: Manual History-Footnote-269626 -Node: How To Contribute69700 -Node: Acknowledgments70626 -Node: Getting Started75563 -Node: Running gawk78002 -Node: One-shot79192 -Node: Read Terminal80455 -Node: Long82448 -Node: Executable Scripts83961 -Ref: Executable Scripts-Footnote-186594 -Node: Comments86697 -Node: Quoting89181 -Node: DOS Quoting94707 -Node: Sample Data Files96763 -Node: Very Simple99358 -Node: Two Rules105460 -Node: More Complex107345 -Node: Statements/Lines109677 -Ref: Statements/Lines-Footnote-1114161 -Node: Other Features114426 -Node: When115362 -Ref: When-Footnote-1117116 -Node: Intro Summary117181 -Node: Invoking Gawk118065 -Node: Command Line119579 -Node: Options120377 -Ref: Options-Footnote-1138291 -Ref: Options-Footnote-2138522 -Node: Other Arguments138547 -Node: Naming Standard Input142558 -Node: Environment Variables143768 -Node: AWKPATH Variable144326 -Ref: AWKPATH Variable-Footnote-1147738 -Ref: AWKPATH Variable-Footnote-2147772 -Node: AWKLIBPATH Variable148143 -Ref: AWKLIBPATH Variable-Footnote-1149840 -Node: Other Environment Variables150215 -Node: Exit Status154036 -Node: Include Files154713 -Node: Loading Shared Libraries158403 -Node: Obsolete159831 -Node: Undocumented160523 -Node: Invoking Summary160820 -Node: Regexp163661 -Node: Regexp Usage165115 -Node: Escape Sequences167152 -Node: Regexp Operators173393 -Node: Regexp Operator Details173878 -Ref: Regexp Operator Details-Footnote-1180310 -Node: Interval Expressions180457 -Ref: Interval Expressions-Footnote-1181878 -Node: Bracket Expressions181976 -Ref: table-char-classes184452 -Node: Leftmost Longest187778 -Node: Computed Regexps189081 -Node: GNU Regexp Operators192508 -Node: Case-sensitivity196245 -Ref: Case-sensitivity-Footnote-1199111 -Ref: Case-sensitivity-Footnote-2199346 -Node: Regexp Summary199454 -Node: Reading Files200920 -Node: Records203189 -Node: awk split records204264 -Node: gawk split records208964 -Ref: gawk split records-Footnote-1214038 -Node: Fields214075 -Node: Nonconstant Fields216816 -Ref: Nonconstant Fields-Footnote-1219052 -Node: Changing Fields219256 -Node: Field Separators225287 -Node: Default Field Splitting227985 -Node: Regexp Field Splitting229103 -Node: Single Character Fields232780 -Node: Command Line Field Separator233840 -Node: Full Line Fields237058 -Ref: Full Line Fields-Footnote-1238580 -Ref: Full Line Fields-Footnote-2238626 -Node: Field Splitting Summary238727 -Node: Constant Size240801 -Node: Fixed width data241533 -Node: Skipping intervening245000 -Node: Allowing trailing data245798 -Node: Fields with fixed data246835 -Node: Splitting By Content248353 -Ref: Splitting By Content-Footnote-1252136 -Node: More CSV252299 -Node: Testing field creation253891 -Node: Multiple Line255516 -Node: Getline261793 -Node: Plain Getline264262 -Node: Getline/Variable266835 -Node: Getline/File267986 -Node: Getline/Variable/File269374 -Ref: Getline/Variable/File-Footnote-1270979 -Node: Getline/Pipe271067 -Node: Getline/Variable/Pipe273771 -Node: Getline/Coprocess274906 -Node: Getline/Variable/Coprocess276173 -Node: Getline Notes276915 -Node: Getline Summary279712 -Ref: table-getline-variants280136 -Node: Read Timeout280884 -Ref: Read Timeout-Footnote-1284790 -Node: Retrying Input284848 -Node: Command-line directories286047 -Node: Input Summary286953 -Node: Input Exercises290125 -Node: Printing290559 -Node: Print292393 -Node: Print Examples293850 -Node: Output Separators296630 -Node: OFMT298647 -Node: Printf300003 -Node: Basic Printf300788 -Node: Control Letters302362 -Node: Format Modifiers307526 -Node: Printf Examples313541 -Node: Redirection316027 -Node: Special FD322868 -Ref: Special FD-Footnote-1326036 -Node: Special Files326110 -Node: Other Inherited Files326727 -Node: Special Network327728 -Node: Special Caveats328588 -Node: Close Files And Pipes329537 -Ref: table-close-pipe-return-values336444 -Ref: Close Files And Pipes-Footnote-1337257 -Ref: Close Files And Pipes-Footnote-2337405 -Node: Nonfatal337557 -Node: Output Summary339895 -Node: Output Exercises341117 -Node: Expressions341796 -Node: Values342984 -Node: Constants343662 -Node: Scalar Constants344353 -Ref: Scalar Constants-Footnote-1346863 -Node: Nondecimal-numbers347113 -Node: Regexp Constants350114 -Node: Using Constant Regexps350640 -Node: Standard Regexp Constants351262 -Node: Strong Regexp Constants354450 -Node: Variables357462 -Node: Using Variables358119 -Node: Assignment Options360029 -Node: Conversion362500 -Node: Strings And Numbers363024 -Ref: Strings And Numbers-Footnote-1366087 -Node: Locale influences conversions366196 -Ref: table-locale-affects368954 -Node: All Operators369572 -Node: Arithmetic Ops370201 -Node: Concatenation372917 -Ref: Concatenation-Footnote-1375764 -Node: Assignment Ops375871 -Ref: table-assign-ops380862 -Node: Increment Ops382175 -Node: Truth Values and Conditions385635 -Node: Truth Values386709 -Node: Typing and Comparison387757 -Node: Variable Typing388577 -Ref: Variable Typing-Footnote-1395040 -Ref: Variable Typing-Footnote-2395112 -Node: Comparison Operators395189 -Ref: table-relational-ops395608 -Node: POSIX String Comparison399103 -Ref: POSIX String Comparison-Footnote-1400798 -Ref: POSIX String Comparison-Footnote-2400937 -Node: Boolean Ops401021 -Ref: Boolean Ops-Footnote-1405503 -Node: Conditional Exp405595 -Node: Function Calls407331 -Node: Precedence411208 -Node: Locales414867 -Node: Expressions Summary416499 -Node: Patterns and Actions419072 -Node: Pattern Overview420192 -Node: Regexp Patterns421869 -Node: Expression Patterns422411 -Node: Ranges426192 -Node: BEGIN/END429300 -Node: Using BEGIN/END430061 -Ref: Using BEGIN/END-Footnote-1432815 -Node: I/O And BEGIN/END432921 -Node: BEGINFILE/ENDFILE435234 -Node: Empty438465 -Node: Using Shell Variables438782 -Node: Action Overview441056 -Node: Statements443381 -Node: If Statement445229 -Node: While Statement446724 -Node: Do Statement448752 -Node: For Statement449900 -Node: Switch Statement453071 -Node: Break Statement455512 -Node: Continue Statement457604 -Node: Next Statement459431 -Node: Nextfile Statement461814 -Node: Exit Statement464503 -Node: Built-in Variables466906 -Node: User-modified468039 -Node: Auto-set475806 -Ref: Auto-set-Footnote-1492613 -Ref: Auto-set-Footnote-2492819 -Node: ARGC and ARGV492875 -Node: Pattern Action Summary497088 -Node: Arrays499518 -Node: Array Basics500847 -Node: Array Intro501691 -Ref: figure-array-elements503666 -Ref: Array Intro-Footnote-1506370 -Node: Reference to Elements506498 -Node: Assigning Elements508962 -Node: Array Example509453 -Node: Scanning an Array511212 -Node: Controlling Scanning514234 -Ref: Controlling Scanning-Footnote-1520690 -Node: Numeric Array Subscripts521006 -Node: Uninitialized Subscripts523190 -Node: Delete524809 -Ref: Delete-Footnote-1527561 -Node: Multidimensional527618 -Node: Multiscanning530713 -Node: Arrays of Arrays532304 -Node: Arrays Summary537072 -Node: Functions539165 -Node: Built-in540203 -Node: Calling Built-in541284 -Node: Numeric Functions543280 -Ref: Numeric Functions-Footnote-1547308 -Ref: Numeric Functions-Footnote-2547956 -Ref: Numeric Functions-Footnote-3548004 -Node: String Functions548276 -Ref: String Functions-Footnote-1572417 -Ref: String Functions-Footnote-2572545 -Ref: String Functions-Footnote-3572793 -Node: Gory Details572880 -Ref: table-sub-escapes574671 -Ref: table-sub-proposed576190 -Ref: table-posix-sub577553 -Ref: table-gensub-escapes579094 -Ref: Gory Details-Footnote-1579917 -Node: I/O Functions580071 -Ref: table-system-return-values586525 -Ref: I/O Functions-Footnote-1588605 -Ref: I/O Functions-Footnote-2588753 -Node: Time Functions588873 -Ref: Time Functions-Footnote-1599544 -Ref: Time Functions-Footnote-2599612 -Ref: Time Functions-Footnote-3599770 -Ref: Time Functions-Footnote-4599881 -Ref: Time Functions-Footnote-5599993 -Ref: Time Functions-Footnote-6600220 -Node: Bitwise Functions600486 -Ref: table-bitwise-ops601080 -Ref: Bitwise Functions-Footnote-1607143 -Ref: Bitwise Functions-Footnote-2607316 -Node: Type Functions607507 -Node: I18N Functions610370 -Node: User-defined612021 -Node: Definition Syntax612833 -Ref: Definition Syntax-Footnote-1618527 -Node: Function Example618598 -Ref: Function Example-Footnote-1621520 -Node: Function Calling621542 -Node: Calling A Function622130 -Node: Variable Scope623088 -Node: Pass By Value/Reference626082 -Node: Function Caveats628726 -Ref: Function Caveats-Footnote-1630773 -Node: Return Statement630893 -Node: Dynamic Typing633872 -Node: Indirect Calls634802 -Ref: Indirect Calls-Footnote-1645054 -Node: Functions Summary645182 -Node: Library Functions647887 -Ref: Library Functions-Footnote-1651494 -Ref: Library Functions-Footnote-2651637 -Node: Library Names651808 -Ref: Library Names-Footnote-1655475 -Ref: Library Names-Footnote-2655698 -Node: General Functions655784 -Node: Strtonum Function656887 -Node: Assert Function659909 -Node: Round Function663235 -Node: Cliff Random Function664775 -Node: Ordinal Functions665791 -Ref: Ordinal Functions-Footnote-1668854 -Ref: Ordinal Functions-Footnote-2669106 -Node: Join Function669316 -Ref: Join Function-Footnote-1671086 -Node: Getlocaltime Function671286 -Node: Readfile Function675028 -Node: Shell Quoting677005 -Node: Data File Management678406 -Node: Filetrans Function679038 -Node: Rewind Function683134 -Node: File Checking685043 -Ref: File Checking-Footnote-1686377 -Node: Empty Files686578 -Node: Ignoring Assigns688557 -Node: Getopt Function690107 -Ref: Getopt Function-Footnote-1705318 -Node: Passwd Functions705518 -Ref: Passwd Functions-Footnote-1714357 -Node: Group Functions714445 -Ref: Group Functions-Footnote-1722343 -Node: Walking Arrays722550 -Node: Library Functions Summary725558 -Node: Library Exercises726964 -Node: Sample Programs727429 -Node: Running Examples728199 -Node: Clones728927 -Node: Cut Program730151 -Node: Egrep Program740291 -Node: Id Program749292 -Node: Split Program759239 -Ref: Split Program-Footnote-1769129 -Node: Tee Program769302 -Node: Uniq Program772092 -Node: Wc Program779680 -Node: Bytes vs. Characters780077 -Node: Using extensions781625 -Node: wc program782379 -Node: Miscellaneous Programs787244 -Node: Dupword Program788457 -Node: Alarm Program790487 -Node: Translate Program795342 -Ref: Translate Program-Footnote-1799907 -Node: Labels Program800177 -Ref: Labels Program-Footnote-1803528 -Node: Word Sorting803612 -Node: History Sorting807684 -Node: Extract Program809909 -Node: Simple Sed817963 -Node: Igawk Program821037 -Ref: Igawk Program-Footnote-1835368 -Ref: Igawk Program-Footnote-2835570 -Ref: Igawk Program-Footnote-3835692 -Node: Anagram Program835807 -Node: Signature Program838869 -Node: Programs Summary840116 -Node: Programs Exercises841330 -Ref: Programs Exercises-Footnote-1845460 -Node: Advanced Features845546 -Node: Nondecimal Data847613 -Node: Array Sorting849204 -Node: Controlling Array Traversal849904 -Ref: Controlling Array Traversal-Footnote-1858272 -Node: Array Sorting Functions858390 -Ref: Array Sorting Functions-Footnote-1863481 -Node: Two-way I/O863677 -Ref: Two-way I/O-Footnote-1871398 -Ref: Two-way I/O-Footnote-2871585 -Node: TCP/IP Networking871667 -Node: Profiling874785 -Node: Extension Philosophy884094 -Node: Advanced Features Summary885573 -Node: Internationalization887588 -Node: I18N and L10N889068 -Node: Explaining gettext889755 -Ref: Explaining gettext-Footnote-1895647 -Ref: Explaining gettext-Footnote-2895832 -Node: Programmer i18n895997 -Ref: Programmer i18n-Footnote-1900946 -Node: Translator i18n900995 -Node: String Extraction901789 -Ref: String Extraction-Footnote-1902921 -Node: Printf Ordering903007 -Ref: Printf Ordering-Footnote-1905793 -Node: I18N Portability905857 -Ref: I18N Portability-Footnote-1908313 -Node: I18N Example908376 -Ref: I18N Example-Footnote-1911651 -Ref: I18N Example-Footnote-2911724 -Node: Gawk I18N911833 -Node: I18N Summary912482 -Node: Debugger913823 -Node: Debugging914823 -Node: Debugging Concepts915264 -Node: Debugging Terms917073 -Node: Awk Debugging919648 -Ref: Awk Debugging-Footnote-1920593 -Node: Sample Debugging Session920725 -Node: Debugger Invocation921259 -Node: Finding The Bug922645 -Node: List of Debugger Commands929119 -Node: Breakpoint Control930452 -Node: Debugger Execution Control934146 -Node: Viewing And Changing Data937508 -Node: Execution Stack941049 -Node: Debugger Info942686 -Node: Miscellaneous Debugger Commands946757 -Node: Readline Support951819 -Node: Limitations952715 -Node: Debugging Summary955269 -Node: Namespaces956548 -Node: Global Namespace957659 -Node: Qualified Names959057 -Node: Default Namespace960056 -Node: Changing The Namespace960797 -Node: Naming Rules962411 -Node: Internal Name Management964259 -Node: Namespace Example965301 -Node: Namespace And Features967863 -Node: Namespace Summary969298 -Node: Arbitrary Precision Arithmetic970775 -Node: Computer Arithmetic972262 -Ref: table-numeric-ranges976028 -Ref: table-floating-point-ranges976521 -Ref: Computer Arithmetic-Footnote-1977179 -Node: Math Definitions977236 -Ref: table-ieee-formats980552 -Ref: Math Definitions-Footnote-1981155 -Node: MPFR features981260 -Node: FP Math Caution982978 -Ref: FP Math Caution-Footnote-1984050 -Node: Inexactness of computations984419 -Node: Inexact representation985379 -Node: Comparing FP Values986739 -Node: Errors accumulate987980 -Node: Getting Accuracy989413 -Node: Try To Round992123 -Node: Setting precision993022 -Ref: table-predefined-precision-strings993719 -Node: Setting the rounding mode995549 -Ref: table-gawk-rounding-modes995923 -Ref: Setting the rounding mode-Footnote-1999854 -Node: Arbitrary Precision Integers1000033 -Ref: Arbitrary Precision Integers-Footnote-11003208 -Node: Checking for MPFR1003357 -Node: POSIX Floating Point Problems1004831 -Ref: POSIX Floating Point Problems-Footnote-11009116 -Node: Floating point summary1009154 -Node: Dynamic Extensions1011344 -Node: Extension Intro1012897 -Node: Plugin License1014163 -Node: Extension Mechanism Outline1014960 -Ref: figure-load-extension1015399 -Ref: figure-register-new-function1016964 -Ref: figure-call-new-function1018056 -Node: Extension API Description1020118 -Node: Extension API Functions Introduction1021831 -Ref: table-api-std-headers1023667 -Node: General Data Types1027916 -Ref: General Data Types-Footnote-11036546 -Node: Memory Allocation Functions1036845 -Ref: Memory Allocation Functions-Footnote-11041346 -Node: Constructor Functions1041445 -Node: API Ownership of MPFR and GMP Values1044911 -Node: Registration Functions1046224 -Node: Extension Functions1046924 -Node: Exit Callback Functions1052246 -Node: Extension Version String1053496 -Node: Input Parsers1054159 -Node: Output Wrappers1066880 -Node: Two-way processors1071392 -Node: Printing Messages1073657 -Ref: Printing Messages-Footnote-11074828 -Node: Updating ERRNO1074981 -Node: Requesting Values1075720 -Ref: table-value-types-returned1076457 -Node: Accessing Parameters1077393 -Node: Symbol Table Access1078630 -Node: Symbol table by name1079142 -Ref: Symbol table by name-Footnote-11082166 -Node: Symbol table by cookie1082294 -Ref: Symbol table by cookie-Footnote-11086479 -Node: Cached values1086543 -Ref: Cached values-Footnote-11090079 -Node: Array Manipulation1090232 -Ref: Array Manipulation-Footnote-11091323 -Node: Array Data Types1091360 -Ref: Array Data Types-Footnote-11094018 -Node: Array Functions1094110 -Node: Flattening Arrays1098608 -Node: Creating Arrays1105584 -Node: Redirection API1110351 -Node: Extension API Variables1113184 -Node: Extension Versioning1113895 -Ref: gawk-api-version1114324 -Node: Extension GMP/MPFR Versioning1116055 -Node: Extension API Informational Variables1117683 -Node: Extension API Boilerplate1118756 -Node: Changes from API V11122730 -Node: Finding Extensions1124302 -Node: Extension Example1124861 -Node: Internal File Description1125659 -Node: Internal File Ops1129739 -Ref: Internal File Ops-Footnote-11141089 -Node: Using Internal File Ops1141229 -Ref: Using Internal File Ops-Footnote-11143612 -Node: Extension Samples1143886 -Node: Extension Sample File 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Installation1219869 -Node: Gawk Distribution1220813 -Node: Getting1221297 -Node: Extracting1222260 -Node: Distribution contents1223898 -Node: Unix Installation1230378 -Node: Quick Installation1231060 -Node: Shell Startup Files1233474 -Node: Additional Configuration Options1234563 -Node: Configuration Philosophy1236878 -Node: Non-Unix Installation1239247 -Node: PC Installation1239707 -Node: PC Binary Installation1240545 -Node: PC Compiling1240980 -Node: PC Using1242097 -Node: Cygwin1245650 -Node: MSYS1246874 -Node: VMS Installation1247476 -Node: VMS Compilation1248267 -Ref: VMS Compilation-Footnote-11249496 -Node: VMS Dynamic Extensions1249554 -Node: VMS Installation Details1251239 -Node: VMS Running1253492 -Node: VMS GNV1257771 -Node: VMS Old Gawk1258506 -Node: Bugs1258977 -Node: Bug address1259640 -Node: Usenet1262622 -Node: Maintainers1263626 -Node: Other Versions1264811 -Node: Installation summary1272676 -Node: Notes1273885 -Node: Compatibility Mode1274679 -Node: Additions1275461 -Node: Accessing The Source1276386 -Node: Adding Code1277823 -Node: New Ports1284042 -Node: Derived Files1288417 -Ref: Derived Files-Footnote-11294077 -Ref: Derived Files-Footnote-21294112 -Ref: Derived Files-Footnote-31294710 -Node: Future Extensions1294824 -Node: Implementation Limitations1295482 -Node: Extension Design1296692 -Node: Old Extension Problems1297836 -Ref: Old Extension Problems-Footnote-11299354 -Node: Extension New Mechanism Goals1299411 -Ref: Extension New Mechanism Goals-Footnote-11302775 -Node: Extension Other Design Decisions1302964 -Node: Extension Future Growth1305077 -Node: Notes summary1305683 -Node: Basic Concepts1306841 -Node: Basic High Level1307522 -Ref: figure-general-flow1307804 -Ref: figure-process-flow1308489 -Ref: Basic High Level-Footnote-11311790 -Node: Basic Data Typing1311975 -Node: Glossary1315303 -Node: Copying1347188 -Node: GNU Free Documentation License1384731 -Node: Index1409851 +Node: Foreword344638 +Node: Foreword449080 +Node: Preface50612 +Ref: Preface-Footnote-153471 +Ref: Preface-Footnote-253580 +Ref: Preface-Footnote-353814 +Node: History53956 +Node: Names56308 +Ref: Names-Footnote-157412 +Node: This Manual57559 +Ref: This Manual-Footnote-164198 +Node: Conventions64298 +Node: Manual History66667 +Ref: Manual History-Footnote-169664 +Ref: Manual History-Footnote-269705 +Node: How To Contribute69779 +Node: Acknowledgments70705 +Node: Getting Started75642 +Node: Running gawk78081 +Node: One-shot79271 +Node: Read Terminal80534 +Node: Long82527 +Node: Executable Scripts84040 +Ref: Executable Scripts-Footnote-186673 +Node: Comments86776 +Node: Quoting89260 +Node: DOS Quoting94786 +Node: Sample Data Files96842 +Node: Very Simple99437 +Node: Two Rules105539 +Node: More Complex107424 +Node: Statements/Lines109756 +Ref: Statements/Lines-Footnote-1114240 +Node: Other Features114505 +Node: When115441 +Ref: When-Footnote-1117195 +Node: Intro Summary117260 +Node: Invoking Gawk118144 +Node: Command Line119658 +Node: Options120456 +Ref: Options-Footnote-1138370 +Ref: Options-Footnote-2138601 +Node: Other Arguments138626 +Node: Naming Standard Input142637 +Node: Environment Variables143847 +Node: AWKPATH Variable144405 +Ref: AWKPATH Variable-Footnote-1147817 +Ref: AWKPATH Variable-Footnote-2147851 +Node: AWKLIBPATH Variable148222 +Ref: AWKLIBPATH Variable-Footnote-1149919 +Node: Other Environment Variables150294 +Node: Exit Status154115 +Node: Include Files154792 +Node: Loading Shared Libraries158482 +Node: Obsolete159910 +Node: Undocumented160602 +Node: Invoking Summary160899 +Node: Regexp163740 +Node: Regexp Usage165194 +Node: Escape Sequences167231 +Node: Regexp Operators173472 +Node: Regexp Operator Details173957 +Ref: Regexp Operator Details-Footnote-1180389 +Node: Interval Expressions180536 +Ref: Interval Expressions-Footnote-1181957 +Node: Bracket Expressions182055 +Ref: table-char-classes184531 +Node: Leftmost Longest187857 +Node: Computed Regexps189160 +Node: GNU Regexp Operators192587 +Node: Case-sensitivity196324 +Ref: Case-sensitivity-Footnote-1199190 +Ref: Case-sensitivity-Footnote-2199425 +Node: Regexp Summary199533 +Node: Reading Files200999 +Node: Records203268 +Node: awk split records204343 +Node: gawk split records209043 +Ref: gawk split records-Footnote-1214117 +Node: Fields214154 +Node: Nonconstant Fields216895 +Ref: Nonconstant Fields-Footnote-1219131 +Node: Changing Fields219335 +Node: Field Separators225366 +Node: Default Field Splitting228064 +Node: Regexp Field Splitting229182 +Node: Single Character Fields232859 +Node: Command Line Field Separator233919 +Node: Full Line Fields237137 +Ref: Full Line Fields-Footnote-1238659 +Ref: Full Line Fields-Footnote-2238705 +Node: Field Splitting Summary238806 +Node: Constant Size240880 +Node: Fixed width data241612 +Node: Skipping intervening245079 +Node: Allowing trailing data245877 +Node: Fields with fixed data246914 +Node: Splitting By Content248432 +Ref: Splitting By Content-Footnote-1252215 +Node: More CSV252378 +Node: Testing field creation253970 +Node: Multiple Line255595 +Node: Getline261872 +Node: Plain Getline264341 +Node: Getline/Variable266914 +Node: Getline/File268065 +Node: Getline/Variable/File269453 +Ref: Getline/Variable/File-Footnote-1271058 +Node: Getline/Pipe271146 +Node: Getline/Variable/Pipe273850 +Node: Getline/Coprocess274985 +Node: Getline/Variable/Coprocess276252 +Node: Getline Notes276994 +Node: Getline Summary279791 +Ref: table-getline-variants280215 +Node: Read Timeout280963 +Ref: Read Timeout-Footnote-1284869 +Node: Retrying Input284927 +Node: Command-line directories286126 +Node: Input Summary287032 +Node: Input Exercises290204 +Node: Printing290638 +Node: Print292472 +Node: Print Examples293929 +Node: Output Separators296709 +Node: OFMT298726 +Node: Printf300082 +Node: Basic Printf300867 +Node: Control Letters302441 +Node: Format Modifiers307603 +Node: Printf Examples313618 +Node: Redirection316104 +Node: Special FD322945 +Ref: Special FD-Footnote-1326113 +Node: Special Files326187 +Node: Other Inherited Files326804 +Node: Special Network327805 +Node: Special Caveats328665 +Node: Close Files And Pipes329614 +Ref: table-close-pipe-return-values336521 +Ref: Close Files And Pipes-Footnote-1337334 +Ref: Close Files And Pipes-Footnote-2337482 +Node: Nonfatal337634 +Node: Output Summary339972 +Node: Output Exercises341194 +Node: Expressions341873 +Node: Values343061 +Node: Constants343739 +Node: Scalar Constants344430 +Ref: Scalar Constants-Footnote-1346940 +Node: Nondecimal-numbers347190 +Node: Regexp Constants350191 +Node: Using Constant Regexps350717 +Node: Standard Regexp Constants351339 +Node: Strong Regexp Constants354527 +Node: Variables357539 +Node: Using Variables358196 +Node: Assignment Options360106 +Node: Conversion362577 +Node: Strings And Numbers363101 +Ref: Strings And Numbers-Footnote-1366164 +Node: Locale influences conversions366273 +Ref: table-locale-affects369031 +Node: All Operators369649 +Node: Arithmetic Ops370278 +Node: 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Callback Functions1054627 +Node: Extension Version String1055877 +Node: Input Parsers1056540 +Node: Output Wrappers1069261 +Node: Two-way processors1073773 +Node: Printing Messages1076038 +Ref: Printing Messages-Footnote-11077209 +Node: Updating ERRNO1077362 +Node: Requesting Values1078101 +Ref: table-value-types-returned1078838 +Node: Accessing Parameters1079774 +Node: Symbol Table Access1081011 +Node: Symbol table by name1081523 +Ref: Symbol table by name-Footnote-11084547 +Node: Symbol table by cookie1084675 +Ref: Symbol table by cookie-Footnote-11088860 +Node: Cached values1088924 +Ref: Cached values-Footnote-11092460 +Node: Array Manipulation1092613 +Ref: Array Manipulation-Footnote-11093704 +Node: Array Data Types1093741 +Ref: Array Data Types-Footnote-11096399 +Node: Array Functions1096491 +Node: Flattening Arrays1100989 +Node: Creating Arrays1107965 +Node: Redirection API1112732 +Node: Extension API Variables1115565 +Node: Extension Versioning1116276 +Ref: gawk-api-version1116705 +Node: Extension GMP/MPFR Versioning1118436 +Node: Extension API Informational Variables1120064 +Node: Extension API Boilerplate1121137 +Node: Changes from API V11125111 +Node: Finding Extensions1126683 +Node: Extension Example1127242 +Node: Internal File Description1128040 +Node: Internal File Ops1132120 +Ref: Internal File Ops-Footnote-11143470 +Node: Using Internal File Ops1143610 +Ref: Using Internal File Ops-Footnote-11145993 +Node: Extension Samples1146267 +Node: Extension Sample File Functions1147796 +Node: Extension Sample Fnmatch1155445 +Node: Extension Sample Fork1156932 +Node: Extension Sample Inplace1158150 +Node: Extension Sample Ord1161776 +Node: Extension Sample Readdir1162612 +Ref: table-readdir-file-types1163501 +Node: Extension Sample Revout1164568 +Node: Extension Sample Rev2way1165157 +Node: Extension Sample Read write array1165897 +Node: Extension Sample Readfile1167839 +Node: Extension Sample Time1168934 +Node: Extension Sample API Tests1170686 +Node: gawkextlib1171178 +Node: Extension summary1174096 +Node: Extension Exercises1177798 +Node: Language History1179040 +Node: V7/SVR3.11180696 +Node: SVR41182848 +Node: POSIX1184282 +Node: BTL1185663 +Node: POSIX/GNU1186392 +Node: Feature History1192170 +Node: Common Extensions1208489 +Node: Ranges and Locales1209772 +Ref: Ranges and Locales-Footnote-11214388 +Ref: Ranges and Locales-Footnote-21214415 +Ref: Ranges and Locales-Footnote-31214650 +Node: Contributors1214873 +Node: History summary1220870 +Node: Installation1222250 +Node: Gawk Distribution1223194 +Node: Getting1223678 +Node: Extracting1224641 +Node: Distribution contents1226279 +Node: Unix Installation1232759 +Node: Quick Installation1233441 +Node: Shell Startup Files1235855 +Node: Additional Configuration Options1236944 +Node: Configuration Philosophy1239259 +Node: Non-Unix Installation1241628 +Node: PC Installation1242088 +Node: PC Binary Installation1242926 +Node: PC Compiling1243361 +Node: PC Using1244478 +Node: Cygwin1248031 +Node: MSYS1249255 +Node: VMS Installation1249857 +Node: VMS Compilation1250648 +Ref: VMS Compilation-Footnote-11251877 +Node: VMS Dynamic Extensions1251935 +Node: VMS Installation Details1253620 +Node: VMS Running1255873 +Node: VMS GNV1260152 +Node: VMS Old Gawk1260887 +Node: Bugs1261358 +Node: Bug address1262021 +Node: Usenet1265003 +Node: Maintainers1266007 +Node: Other Versions1267192 +Node: Installation summary1275057 +Node: Notes1276266 +Node: Compatibility Mode1277060 +Node: Additions1277842 +Node: Accessing The Source1278767 +Node: Adding Code1280204 +Node: New Ports1286423 +Node: Derived Files1290798 +Ref: Derived Files-Footnote-11296458 +Ref: Derived Files-Footnote-21296493 +Ref: Derived Files-Footnote-31297091 +Node: Future Extensions1297205 +Node: Implementation Limitations1297863 +Node: Extension Design1299073 +Node: Old Extension Problems1300217 +Ref: Old Extension Problems-Footnote-11301735 +Node: Extension New Mechanism Goals1301792 +Ref: Extension New Mechanism Goals-Footnote-11305156 +Node: Extension Other Design Decisions1305345 +Node: Extension Future Growth1307458 +Node: Notes summary1308064 +Node: Basic Concepts1309222 +Node: Basic High Level1309903 +Ref: figure-general-flow1310185 +Ref: figure-process-flow1310870 +Ref: Basic High Level-Footnote-11314171 +Node: Basic Data Typing1314356 +Node: Glossary1317684 +Node: Copying1349569 +Node: GNU Free Documentation License1387112 +Node: Index1412232 End Tag Table diff --git a/doc/gawk.texi b/doc/gawk.texi index f3d3b390..4a0fb3ae 100644 --- a/doc/gawk.texi +++ b/doc/gawk.texi @@ -920,6 +920,7 @@ particular records in a file and perform operations upon them. * Inexact representation:: Numbers are not exactly represented. * Comparing FP Values:: How to compare floating point values. * Errors accumulate:: Errors get bigger as they go. +* Strange values:: A few words about infinities and NaNs. * Getting Accuracy:: Getting more accuracy takes some work. * Try To Round:: Add digits and round. * Setting precision:: How to set the precision. @@ -3136,11 +3137,12 @@ column means that the person is a friend. An @samp{R} means that the person is a relative: @example -@c system if test ! -d eg ; then mkdir eg ; fi -@c system if test ! -d eg/lib ; then mkdir eg/lib ; fi -@c system if test ! -d eg/data ; then mkdir eg/data ; fi -@c system if test ! -d eg/prog ; then mkdir eg/prog ; fi -@c system if test ! -d eg/misc ; then mkdir eg/misc ; fi +@c system if test ! -d eg ; then mkdir eg ; fi +@c system if test ! -d eg/lib ; then mkdir eg/lib ; fi +@c system if test ! -d eg/data ; then mkdir eg/data ; fi +@c system if test ! -d eg/prog ; then mkdir eg/prog ; fi +@c system if test ! -d eg/misc ; then mkdir eg/misc ; fi +@c system if test ! -d eg/test-programs ; then mkdir eg/test-programs ; fi @c file eg/data/mail-list Amelia 555-5553 amelia.zodiacusque@@gmail.com F Anthony 555-3412 anthony.asserturo@@hotmail.com A @@ -8442,7 +8444,7 @@ FPAT = "([^,]*)|(\"[^\"]+\")" @c Per email from Ed Morton <mortoneccc@comcast.net> @c @c WONTFIX: 10/2020 -@c This is too much work. FPAT and CSV files are very flakey and +@c This is too much work. FPAT and CSV files are very flaky and @c fragile. Doing something like this is merely inviting trouble. As with @code{FS}, the @code{IGNORECASE} variable (@pxref{User-modified}) @@ -10101,7 +10103,7 @@ infinity are formatted as and positive infinity as @samp{inf} or @samp{infinity}. The special ``not a number'' value formats as @samp{-nan} or @samp{nan} -(@pxref{Math Definitions}). +(@pxref{Strange values}). @item @code{%F} Like @samp{%f}, but the infinity and ``not a number'' values are spelled @@ -18337,7 +18339,7 @@ compatibility mode (@pxref{Options}). @cindexawkfunc{log} @cindex logarithm Return the natural logarithm of @var{x}, if @var{x} is positive; -otherwise, return @code{NaN} (``not a number'') on IEEE 754 systems. +otherwise, return NaN (``not a number'') on IEEE 754 systems. Additionally, @command{gawk} prints a warning message when @code{x} is negative. @@ -33683,21 +33685,9 @@ A special value representing infinity. Operations involving another number and infinity produce infinity. @item NaN -``Not a number.''@footnote{Thanks to Michael Brennan for this description, -which we have paraphrased, and for the examples.} A special value that -results from attempting a calculation that has no answer as a real number. -In such a case, programs can either receive a floating-point exception, -or get @code{NaN} back as the result. The IEEE 754 standard recommends -that systems return @code{NaN}. Some examples: - -@table @code -@item sqrt(-1) -This makes sense in the range of complex numbers, but not in the -range of real numbers, so the result is @code{NaN}. - -@item log(-8) -@minus{}8 is out of the domain of @code{log()}, so the result is @code{NaN}. -@end table +``Not a number.'' A special value that results from attempting a +calculation that has no answer as a real number. @xref{Strange values}, +for more information about infinity and not-a-number values. @item Normalized How the significand (see later in this list) is usually stored. The @@ -33866,6 +33856,7 @@ decimal places in the final result. * Inexact representation:: Numbers are not exactly represented. * Comparing FP Values:: How to compare floating point values. * Errors accumulate:: Errors get bigger as they go. +* Strange values:: A few words about infinities and NaNs. @end menu @node Inexact representation @@ -33987,6 +33978,242 @@ $ @kbd{gawk 'BEGIN @{} @print{} 4 @end example +@node Strange values +@subsubsection Floating Point Values They Didn't Talk About In School + +Both IEEE 754 floating-point hardware, and MPFR, support two kinds of +values that you probably didn't learn about in school. The first is +@dfn{infinity}, a special value, that can be either negative or positive, +and which is either smaller than any other value (negative infinity), +or larger than any other value (positive infinity). When such values +are generated, @command{gawk} prints them as either @samp{-inf} or +@samp{+inf}, respectively. It accepts those strings as data input and +converts them to the proper floating-point values internally. + +Infinity values of the same sign compare as equal to each other. +Otherwise, operations (addition, subtraction, etc.) involving another +number and infinity produce mathematically reasonable results. + +The second kind of value is ``not a number'', or NaN for +short.@footnote{Thanks to Michael Brennan for this description, which we +have paraphrased, and for the examples.} This is a special value that results +from attempting a calculation that has no answer as a real number. +In such a case, programs can either receive a floating-point exception, +or get NaN back as the result. The IEEE 754 standard recommends +that systems return NaN. Some examples: + +@table @code +@item sqrt(-1) +@iftex +The @math{\sqrt{-1}} +@end iftex +@ifnottex +This +@end ifnottex +makes sense in the range of complex numbers, but not in the +range of real numbers, so the result is NaN. + +@item log(-8) +@minus{}8 is out of the domain of @code{log()}, so the result is NaN. +@end table + +NaN values are strange. In particular, they cannot be compared with other +floating point values; any such comparison, except for ``is not equal +to'', returns false. NaN values are so much unequal to other values that +even comparing two identical NaN values with @code{!=} returns true! + +NaN values can also be signed, although it depends upon the implementation +as to which sign you get for any operation that returns a NaN. For +example, on some systems, @code{sqrt(-1)} returns a negative NaN. On +others, it returns a positive NaN. + +When such values are generated, @command{gawk} prints them as either +@samp{-nan} or @samp{+nan}, respectively. Here too, @command{gawk} +accepts those strings as data input and converts them to the proper +floating-point values internally. + +If you want to dive more deeply into this topic, you can find +test programs in C, @command{awk} and Python in the directory +@file{awklib/eg/test-programs} in the @command{gawk} distribution. +These programs enable comparison among programming languages as to how +they handle NaN and infinity values. + +@ignore +@c file eg/test-programs/gen-float-table.awk +function eq(left, right) +{ + return left == right +} + +function ne(left, right) +{ + return left != right +} + +function lt(left, right) +{ + return left < right +} + +function le(left, right) +{ + return left <= right +} + +function gt(left, right) +{ + return left > right +} + +function ge(left, right) +{ + return left >= right +} + +BEGIN { + nan = sqrt(-1) + inf = -log(0) + split("== != < <= > >=", names) + names[3] = names[3] " " + names[5] = names[5] " " + split("eq ne lt le gt ge", funcs) + + compare[1] = 2.0 + compare[2] = values[1] = -sqrt(-1.0) # nan + compare[3] = values[2] = sqrt(-1.0) # -nan + compare[4] = values[3] = -log(0.0) # inf + compare[5] = values[4] = log(0.0) # -inf + + for (i = 1; i in values; i++) { + for (j = 1; j in compare; j++) { + for (k = 1; k in names; k++) { + the_func = funcs[k] + printf("%g %s %g -> %s\n", + values[i], + names[k], + compare[j], + @the_func(values[i], compare[j]) ? + "true" : "false"); + } + printf("\n"); + } + } +} +@c endfile +@end ignore + +@ignore +@c file eg/test-programs/gen-float-table.c +#include <stdio.h> +#include <math.h> +#include <stdbool.h> + +#define def_func(name, op) \ + bool name(double left, double right) { \ + return left op right; \ + } + +def_func(eq, ==) +def_func(ne, !=) +def_func(lt, <) +def_func(le, <=) +def_func(gt, >) +def_func(ge, >=) + +struct { + const char *name; + bool (*func)(double left, double right); +} functions[] = { + { "==", eq }, + { "!=", ne }, + { "< ", lt }, + { "<=", le }, + { "> ", gt }, + { ">=", ge }, + { 0, 0 } +}; + +int main() +{ + double values[] = { + -sqrt(-1), // nan + sqrt(-1), // -nan + -log(0.0), // inf + log(0.0) // -inf + }; + double compare[] = { 2.0, + -sqrt(-1), // nan + sqrt(-1), // -nan + -log(0.0), // inf + log(0.0) // -inf + }; + + int i, j, k; + + for (i = 0; i < 4; i++) { + for (j = 0; j < 5; j++) { + for (k = 0; functions[k].name != NULL; k++) { + printf("%g %s %g -> %s\n", values[i], + functions[k].name, + compare[j], + functions[k].func(values[i], compare[j]) ? "true" : "false"); + } + printf("\n"); + } + } + + return 0; +} +@c endfile +@end ignore + +@ignore +@c file eg/test-programs/gen-float-table.py +from math import * + +nan = float('NaN') +inf = float('Inf') + +def eq(left, right): + return left == right + +def ne(left, right): + return left != right + +def lt(left, right): + return left < right + +def le(left, right): + return left <= right + +def gt(left, right): + return left > right + +def ge(left, right): + return left >= right + +func_map = { + "==": eq, + "!=": ne, + "< ": lt, + "<=": le, + "> ": gt, + ">=": ge, +} + +compare = [2.0, nan, -nan, inf, -inf] +values = [nan, -nan, inf, -inf] + +for i in range(len(values)): + for j in range(len(compare)): + for op in func_map: + print("%g %s %g -> %s" % + (values[i], op, compare[j], func_map[op](values[i], compare[j]))) + + print("") +@c endfile +@end ignore + @node Getting Accuracy @subsection Getting the Accuracy You Need diff --git a/doc/gawktexi.in b/doc/gawktexi.in index ab2c1b4e..6e9930d1 100644 --- a/doc/gawktexi.in +++ b/doc/gawktexi.in @@ -915,6 +915,7 @@ particular records in a file and perform operations upon them. * Inexact representation:: Numbers are not exactly represented. * Comparing FP Values:: How to compare floating point values. * Errors accumulate:: Errors get bigger as they go. +* Strange values:: A few words about infinities and NaNs. * Getting Accuracy:: Getting more accuracy takes some work. * Try To Round:: Add digits and round. * Setting precision:: How to set the precision. @@ -3046,11 +3047,12 @@ column means that the person is a friend. An @samp{R} means that the person is a relative: @example -@c system if test ! -d eg ; then mkdir eg ; fi -@c system if test ! -d eg/lib ; then mkdir eg/lib ; fi -@c system if test ! -d eg/data ; then mkdir eg/data ; fi -@c system if test ! -d eg/prog ; then mkdir eg/prog ; fi -@c system if test ! -d eg/misc ; then mkdir eg/misc ; fi +@c system if test ! -d eg ; then mkdir eg ; fi +@c system if test ! -d eg/lib ; then mkdir eg/lib ; fi +@c system if test ! -d eg/data ; then mkdir eg/data ; fi +@c system if test ! -d eg/prog ; then mkdir eg/prog ; fi +@c system if test ! -d eg/misc ; then mkdir eg/misc ; fi +@c system if test ! -d eg/test-programs ; then mkdir eg/test-programs ; fi @c file eg/data/mail-list Amelia 555-5553 amelia.zodiacusque@@gmail.com F Anthony 555-3412 anthony.asserturo@@hotmail.com A @@ -7965,7 +7967,7 @@ FPAT = "([^,]*)|(\"[^\"]+\")" @c Per email from Ed Morton <mortoneccc@comcast.net> @c @c WONTFIX: 10/2020 -@c This is too much work. FPAT and CSV files are very flakey and +@c This is too much work. FPAT and CSV files are very flaky and @c fragile. Doing something like this is merely inviting trouble. As with @code{FS}, the @code{IGNORECASE} variable (@pxref{User-modified}) @@ -9624,7 +9626,7 @@ infinity are formatted as and positive infinity as @samp{inf} or @samp{infinity}. The special ``not a number'' value formats as @samp{-nan} or @samp{nan} -(@pxref{Math Definitions}). +(@pxref{Strange values}). @item @code{%F} Like @samp{%f}, but the infinity and ``not a number'' values are spelled @@ -17532,7 +17534,7 @@ compatibility mode (@pxref{Options}). @cindexawkfunc{log} @cindex logarithm Return the natural logarithm of @var{x}, if @var{x} is positive; -otherwise, return @code{NaN} (``not a number'') on IEEE 754 systems. +otherwise, return NaN (``not a number'') on IEEE 754 systems. Additionally, @command{gawk} prints a warning message when @code{x} is negative. @@ -32619,21 +32621,9 @@ A special value representing infinity. Operations involving another number and infinity produce infinity. @item NaN -``Not a number.''@footnote{Thanks to Michael Brennan for this description, -which we have paraphrased, and for the examples.} A special value that -results from attempting a calculation that has no answer as a real number. -In such a case, programs can either receive a floating-point exception, -or get @code{NaN} back as the result. The IEEE 754 standard recommends -that systems return @code{NaN}. Some examples: - -@table @code -@item sqrt(-1) -This makes sense in the range of complex numbers, but not in the -range of real numbers, so the result is @code{NaN}. - -@item log(-8) -@minus{}8 is out of the domain of @code{log()}, so the result is @code{NaN}. -@end table +``Not a number.'' A special value that results from attempting a +calculation that has no answer as a real number. @xref{Strange values}, +for more information about infinity and not-a-number values. @item Normalized How the significand (see later in this list) is usually stored. The @@ -32802,6 +32792,7 @@ decimal places in the final result. * Inexact representation:: Numbers are not exactly represented. * Comparing FP Values:: How to compare floating point values. * Errors accumulate:: Errors get bigger as they go. +* Strange values:: A few words about infinities and NaNs. @end menu @node Inexact representation @@ -32923,6 +32914,242 @@ $ @kbd{gawk 'BEGIN @{} @print{} 4 @end example +@node Strange values +@subsubsection Floating Point Values They Didn't Talk About In School + +Both IEEE 754 floating-point hardware, and MPFR, support two kinds of +values that you probably didn't learn about in school. The first is +@dfn{infinity}, a special value, that can be either negative or positive, +and which is either smaller than any other value (negative infinity), +or larger than any other value (positive infinity). When such values +are generated, @command{gawk} prints them as either @samp{-inf} or +@samp{+inf}, respectively. It accepts those strings as data input and +converts them to the proper floating-point values internally. + +Infinity values of the same sign compare as equal to each other. +Otherwise, operations (addition, subtraction, etc.) involving another +number and infinity produce mathematically reasonable results. + +The second kind of value is ``not a number'', or NaN for +short.@footnote{Thanks to Michael Brennan for this description, which we +have paraphrased, and for the examples.} This is a special value that results +from attempting a calculation that has no answer as a real number. +In such a case, programs can either receive a floating-point exception, +or get NaN back as the result. The IEEE 754 standard recommends +that systems return NaN. Some examples: + +@table @code +@item sqrt(-1) +@iftex +The @math{\sqrt{-1}} +@end iftex +@ifnottex +This +@end ifnottex +makes sense in the range of complex numbers, but not in the +range of real numbers, so the result is NaN. + +@item log(-8) +@minus{}8 is out of the domain of @code{log()}, so the result is NaN. +@end table + +NaN values are strange. In particular, they cannot be compared with other +floating point values; any such comparison, except for ``is not equal +to'', returns false. NaN values are so much unequal to other values that +even comparing two identical NaN values with @code{!=} returns true! + +NaN values can also be signed, although it depends upon the implementation +as to which sign you get for any operation that returns a NaN. For +example, on some systems, @code{sqrt(-1)} returns a negative NaN. On +others, it returns a positive NaN. + +When such values are generated, @command{gawk} prints them as either +@samp{-nan} or @samp{+nan}, respectively. Here too, @command{gawk} +accepts those strings as data input and converts them to the proper +floating-point values internally. + +If you want to dive more deeply into this topic, you can find +test programs in C, @command{awk} and Python in the directory +@file{awklib/eg/test-programs} in the @command{gawk} distribution. +These programs enable comparison among programming languages as to how +they handle NaN and infinity values. + +@ignore +@c file eg/test-programs/gen-float-table.awk +function eq(left, right) +{ + return left == right +} + +function ne(left, right) +{ + return left != right +} + +function lt(left, right) +{ + return left < right +} + +function le(left, right) +{ + return left <= right +} + +function gt(left, right) +{ + return left > right +} + +function ge(left, right) +{ + return left >= right +} + +BEGIN { + nan = sqrt(-1) + inf = -log(0) + split("== != < <= > >=", names) + names[3] = names[3] " " + names[5] = names[5] " " + split("eq ne lt le gt ge", funcs) + + compare[1] = 2.0 + compare[2] = values[1] = -sqrt(-1.0) # nan + compare[3] = values[2] = sqrt(-1.0) # -nan + compare[4] = values[3] = -log(0.0) # inf + compare[5] = values[4] = log(0.0) # -inf + + for (i = 1; i in values; i++) { + for (j = 1; j in compare; j++) { + for (k = 1; k in names; k++) { + the_func = funcs[k] + printf("%g %s %g -> %s\n", + values[i], + names[k], + compare[j], + @the_func(values[i], compare[j]) ? + "true" : "false"); + } + printf("\n"); + } + } +} +@c endfile +@end ignore + +@ignore +@c file eg/test-programs/gen-float-table.c +#include <stdio.h> +#include <math.h> +#include <stdbool.h> + +#define def_func(name, op) \ + bool name(double left, double right) { \ + return left op right; \ + } + +def_func(eq, ==) +def_func(ne, !=) +def_func(lt, <) +def_func(le, <=) +def_func(gt, >) +def_func(ge, >=) + +struct { + const char *name; + bool (*func)(double left, double right); +} functions[] = { + { "==", eq }, + { "!=", ne }, + { "< ", lt }, + { "<=", le }, + { "> ", gt }, + { ">=", ge }, + { 0, 0 } +}; + +int main() +{ + double values[] = { + -sqrt(-1), // nan + sqrt(-1), // -nan + -log(0.0), // inf + log(0.0) // -inf + }; + double compare[] = { 2.0, + -sqrt(-1), // nan + sqrt(-1), // -nan + -log(0.0), // inf + log(0.0) // -inf + }; + + int i, j, k; + + for (i = 0; i < 4; i++) { + for (j = 0; j < 5; j++) { + for (k = 0; functions[k].name != NULL; k++) { + printf("%g %s %g -> %s\n", values[i], + functions[k].name, + compare[j], + functions[k].func(values[i], compare[j]) ? "true" : "false"); + } + printf("\n"); + } + } + + return 0; +} +@c endfile +@end ignore + +@ignore +@c file eg/test-programs/gen-float-table.py +from math import * + +nan = float('NaN') +inf = float('Inf') + +def eq(left, right): + return left == right + +def ne(left, right): + return left != right + +def lt(left, right): + return left < right + +def le(left, right): + return left <= right + +def gt(left, right): + return left > right + +def ge(left, right): + return left >= right + +func_map = { + "==": eq, + "!=": ne, + "< ": lt, + "<=": le, + "> ": gt, + ">=": ge, +} + +compare = [2.0, nan, -nan, inf, -inf] +values = [nan, -nan, inf, -inf] + +for i in range(len(values)): + for j in range(len(compare)): + for op in func_map: + print("%g %s %g -> %s" % + (values[i], op, compare[j], func_map[op](values[i], compare[j]))) + + print("") +@c endfile +@end ignore + @node Getting Accuracy @subsection Getting the Accuracy You Need diff --git a/doc/it/ChangeLog b/doc/it/ChangeLog index 863eef47..5a6bd03d 100644 --- a/doc/it/ChangeLog +++ b/doc/it/ChangeLog @@ -1,3 +1,7 @@ +2020-11-20 Antonio Giovanni Colombo <azc100@gmail.com> + + * gawktexi.in: Updated. + 2020-11-01 Antonio Giovanni Colombo <azc100@gmail.com> * texinfo.tex: Updated. diff --git a/doc/it/gawktexi.in b/doc/it/gawktexi.in index fe7c6b29..a8c0874f 100644..100755 --- a/doc/it/gawktexi.in +++ b/doc/it/gawktexi.in @@ -1065,13 +1065,14 @@ Copyright dell'edizione italiana @copyright{} 2016 -- Free Software Foundation, esattamente. * Confronti tra valori in VM:: Come confrontare valori in virgola mobile. * Gli errori si sommano:: Gli errori diventano sempre maggiori. +* Valori strani:: Un cenno riguardo ai valori infiniti e a NaN [``non @`e un numero'']. * Ottenere la precisione:: Ottenere la precisione voluta. * Tentare di arrotondare:: Tentare di aggiungere bit di precisione e arrotondare. * Impostare la precisione:: Impostare la precisione. * Impostare modo di arrotondare:: Impostare la modalit@`a di arrotondamento. -* Controllare disponibilit@`a MPFR:: Come controllare se MPFR @`e disponibile. +* Controllare disponibilit@`a MPFR:: Come controllare se MPFR @`e disponibile. * Interi a precisione arbitraria:: Aritmetica dei numeri interi a precisione arbitraria con @command{gawk}. * Problemi virgola mobile POSIX:: Confronto tra standard e uso corrente. @@ -3338,11 +3339,12 @@ persona @`e un amico [Friend]. Una @samp{R} vuol dire che quella persona @`e un parente [Relative]: @example -@c system if test ! -d eg ; then mkdir eg ; fi -@c system if test ! -d eg/lib ; then mkdir eg/lib ; fi -@c system if test ! -d eg/data ; then mkdir eg/data ; fi -@c system if test ! -d eg/prog ; then mkdir eg/prog ; fi -@c system if test ! -d eg/misc ; then mkdir eg/misc ; fi +@c system if test ! -d eg ; then mkdir eg ; fi +@c system if test ! -d eg/lib ; then mkdir eg/lib ; fi +@c system if test ! -d eg/data ; then mkdir eg/data ; fi +@c system if test ! -d eg/prog ; then mkdir eg/prog ; fi +@c system if test ! -d eg/misc ; then mkdir eg/misc ; fi +@c system if test ! -d eg/test-programs ; then mkdir eg/test-programs ; fi @c file eg/data/mail-list Amelia 555-5553 amelia.zodiacusque@@gmail.com F Anthony 555-3412 anthony.asserturo@@hotmail.com A @@ -8710,7 +8712,7 @@ FPAT = "([^,]*)|(\"[^\"]+\")" @c Per email from Ed Morton <mortoneccc@comcast.net> @c @c WONTFIX: 10/2020 -@c This is too much work. FPAT and CSV files are very flakey and +@c This is too much work. FPAT and CSV files are very flaky and @c fragile. Doing something like this is merely inviting trouble. Come per @code{FS}, la variabile @code{IGNORECASE} @@ -10473,9 +10475,9 @@ dallo standard IEEE 754, il valore infinito negativo @`e rappresentato come @samp{-inf} o @samp{-infinity}, e l'infinito positivo come @samp{inf} o @samp{infinity}. -Il valore speciale ``not a number'' [non @`e un numero] viene scritto come +Il valore speciale ``not a number'' ["non @`e un numero"] viene scritto come @samp{-nan} o @samp{nan} -(@pxref{Definizioni matematiche}). +(@pxref{Valori strani}). @item @code{%F} Come @samp{%f}, ma i valori di infinito e di ``not a number'' sono scritti @@ -16060,16 +16062,17 @@ risultato. In @command{gawk}, l'esecuzione di @code{nextfile} produce ulteriori effetti: le eventuali regole @code{ENDFILE} sono eseguite se @command{gawk} non -si trova correntemente all'interno di una regola @code{END} o -@code{BEGINFILE}; @code{ARGIND} @`e +si trova correntemente all'interno di una regola @code{END}, +@code{ARGIND} @`e incrementato e le eventuali regole @code{BEGINFILE} sono eseguite. (@code{ARGIND} non @`e stato ancora trattato. @xref{Variabili predefinite}.) -In @command{gawk}, @code{nextfile} @`e utile all'interno di una regola +C'@`e un ulteriore caso speciale di utilizzo in @command{gawk}. +@code{nextfile} @`e utile all'interno di una regola @code{BEGINFILE} per evitare di elaborare un file che altrimenti causerebbe un errore fatale in @command{gawk}. -In questo caso, le regole @code{ENDFILE} non vengono eseguite. +In questo caso speciale, le regole @code{ENDFILE} non vengono eseguite. @xref{BEGINFILE/ENDFILE}. Sebbene possa sembrare che @samp{close(FILENAME)} ottenga lo stesso @@ -19051,8 +19054,8 @@ modalit@`a compatibile (@pxref{Opzioni}). @cindexawkfunc{log} @cindex logaritmo Restituisce il logaritmo naturale di @var{x}, se @var{x} @`e positivo; -altrimenti, restituisce @code{NaN} (``not a number'') sui sistemi che -implementano lo standard IEEE 754. +altrimenti, restituisce NaN (``not a number'',[``non @`e un numero'']) +sui sistemi che implementano lo standard IEEE 754. Inoltre, @command{gawk} stampa un messaggio di avvertimento qualora @code{x} sia negativo. @@ -35366,23 +35369,10 @@ Come i numeri vanno arrotondati, per eccesso o per difetto, quando necessario. Maggiori dettagli verranno forniti in seguito. @item NaN -``Not a number'' (Non un Numero).@footnote{Grazie a Michael -Brennan per questa descrizione, che abbiamo parafrasato, e per gli esempi.} Un -valore speciale che risulta da un calcolo che non ha risposta come numero -reale. In tal caso, i programmi possono o ricevere un'eccezione di virgola -mobile, o restituire @code{NaN} come risultato. Lo standard IEEE 754 -consiglia che i sistemi restituiscano @code{NaN}. Alcuni esempi: - -@table @code -@item sqrt(-1) -La radice quadrata di @minus{}1 ha senso nell'insieme dei numeri complessi, -ma non nell'insieme dei numeri reali, -per cui il risultato @`e @code{NaN}. - -@item log(-8) -Il logaritmo di @minus{}8 @`e fuori dal dominio di @code{log()}, -per cui il risultato @`e @code{NaN}. -@end table +``Not a number'' (``non @`e un numero''). Un valore speciale +che risulta da un calcolo che non ha come risposta un numero +reale. @xref{Valori strani}, per maggiori informazioni riguardo +ai valori infiniti e ai valori ``non-un-numero''. @item Normalizzato (formato) Come la mantissa (vedi oltre in questa lista) @`e usualmente memorizzata. Il @@ -35534,8 +35524,7 @@ ottenere ulteriori informazioni, e non basarsi solo su quanto qui detto. * Ottenere la precisione:: Ottenere pi@`u precisione richiede qualche sforzo. * Tentare di arrotondare:: Aggiungere cifre di precisione e arrotondare. -* Impostare la precisione:: Come impostare la precisione. -* Impostare modo di arrotondare:: Impostare le modalit@`a di arrotondamento. +* Valori strani:: Un cenno riguardo ai valori infiniti e a NaN [``non @`e un numero'']. @end menu @node Inesattezza nei calcoli @@ -35682,6 +35671,257 @@ $ @kbd{gawk 'BEGIN @{} @print{} 4 @end example +@node Valori strani +@subsubsection Valori in virgola mobile non spiegati a scuola + +Sia l'hardware che implementa lo standard per i numeri in virgola +mobili IEEE 754, che la libreria matematica MPFR, prevedono due +tipi di valori di cui probabilmente non vi hanno parlato a scuola. +Il primo @`e il valore @dfn{infinity} (``infinito''), un valore speciale +che pu@`o avere un segno sia negativo che positivo, e che @`e pi@`u +piccolo di ogni altro valore (infinito negativo), o maggiore di ogni +altro valore (infinito positivo). Quando vengono generati tali valori +@command{gawk} li stampa come @samp{-inf} o @samp{+inf}, rispettivamente. +@command{gawk} accetta queste stringhe come dati in input, e li converte +internamente all'appropriato valore in virgola mobile. + +Valori di infinito che abbiano lo stesso segno risultano uguali +quando sono confrontati fra loro. +Per il resto, altre operazioni (addizione, sottrazione, etc.) +che hanno come operando un infinito e un altro numero producono +risultati matematicamente ragionevoli. + +Il secondo tipo di valore @`e ``not a number'' [``non @`e un numero''] +scritto in forma abbreviata come NaN.@footnote{Grazie a Michael Brennan +per questa descrizione, che abbiamo parafrasato, e per gli esempi.} + +Questo @`e un valore speciale che risulta da un calcolo che non ha come +risposta un numero reale. In tal caso, i programmi possono o ricevere +un’eccezione di virgola mobile, o restituire NaN come risultato. +Lo standard IEEE 754 consiglia che i sistemi restituiscano NaN. +Alcuni esempi: + +@table @code +@item sqrt(-1) +@iftex +La funzione @math{\sqrt{-1}} +@end iftex +@ifnottex +Questa funzione +@end ifnottex +ha senso nell'insieme dei numeri complessi, +ma non nell'insieme dei numeri reali, +per cui il risultato @`e @code{NaN}. + +@item log(-8) +Il logaritmo di @minus{}8 @`e fuori dal dominio di @code{log()}, +per cui il risultato @`e @code{NaN}. +@end table + +I valori Nan sono strani. In particolare, non possono essere confrontati +con altri numeri in virgola mobile; ogni confronto di questo tipo, eccetto +quello ``non uguale a'', restituisce il valore ``falso''. +I valori NaN sono talmente differenti da altri valori che perfino il +confronto di due valori NaN identici fra loro con @code{!=} restituisce +il valore ``vero''! + +I valori NaN possono anche avere un segno (positivo o negativo), +anche se dipende dall'implementazione quale segno viene restituito +da qualsiasi operazione il cui risultato sia un valore NaN. +Per esempio, su alcuni sistemi la funzione @code{sqrt(-1)} +restituisce un NaN negativo. Su altri sistemi il NaN restituito +@`e invece positivo. + +Quando tali valori vengono generati, @command{gawk} li stampa +come @samp{-nan} o @samp{+nan}, rispettivamente. Anche per +questi valori, @command{gawk} accetta queste stringhe come +dati in input e le converte internamente ai valori loro +assegnati come numeri in virgola mobile. + +Se si desidera approfondire ulteriormente questo argomento, si possono +trovare programmi di test scritti in C, @command{awk} e Python +nella directory @file{awklib/eg/test-programs} disponibile +nella distribuzione di @command{gawk}. +Tali programmi permettono un confronto tra i linguaggi di +programmazione, riguardo al modo con cui vengono trattati +i valori di infinito e quelli NaN. + +@ignore +@c file eg/test-programs/gen-float-table.awk +function eq(left, right) +{ + return left == right +} + +function ne(left, right) +{ + return left != right +} + +function lt(left, right) +{ + return left < right +} + +function le(left, right) +{ + return left <= right +} + +function gt(left, right) +{ + return left > right +} + +function ge(left, right) +{ + return left >= right +} + +BEGIN { + nan = sqrt(-1) + inf = -log(0) + split("== != < <= > >=", names) + names[3] = names[3] " " + names[5] = names[5] " " + split("eq ne lt le gt ge", funcs) + + compare[1] = 2.0 + compare[2] = values[1] = -sqrt(-1.0) # nan + compare[3] = values[2] = sqrt(-1.0) # -nan + compare[4] = values[3] = -log(0.0) # inf + compare[5] = values[4] = log(0.0) # -inf + + for (i = 1; i in values; i++) { + for (j = 1; j in compare; j++) { + for (k = 1; k in names; k++) { + the_func = funcs[k] + printf("%g %s %g -> %s\n", + values[i], + names[k], + compare[j], + @the_func(values[i], compare[j]) ? + "true" : "false"); + } + printf("\n"); + } + } +} +@c endfile +@end ignore + +@ignore +@c file eg/test-programs/gen-float-table.c +#include <stdio.h> +#include <math.h> +#include <stdbool.h> + +#define def_func(name, op) \ + bool name(double left, double right) { \ + return left op right; \ + } + +def_func(eq, ==) +def_func(ne, !=) +def_func(lt, <) +def_func(le, <=) +def_func(gt, >) +def_func(ge, >=) + +struct { + const char *name; + bool (*func)(double left, double right); +} functions[] = { + { "==", eq }, + { "!=", ne }, + { "< ", lt }, + { "<=", le }, + { "> ", gt }, + { ">=", ge }, + { 0, 0 } +}; + +int main() +{ + double values[] = { + -sqrt(-1), // nan + sqrt(-1), // -nan + -log(0.0), // inf + log(0.0) // -inf + }; + double compare[] = { 2.0, + -sqrt(-1), // nan + sqrt(-1), // -nan + -log(0.0), // inf + log(0.0) // -inf + }; + + int i, j, k; + + for (i = 0; i < 4; i++) { + for (j = 0; j < 5; j++) { + for (k = 0; functions[k].name != NULL; k++) { + printf("%g %s %g -> %s\n", values[i], + functions[k].name, + compare[j], + functions[k].func(values[i], compare[j]) ? "true" : "false"); + } + printf("\n"); + } + } + + return 0; +} +@c endfile +@end ignore + +@ignore +@c file eg/test-programs/gen-float-table.py +from math import * + +nan = float('NaN') +inf = float('Inf') + +def eq(left, right): + return left == right + +def ne(left, right): + return left != right + +def lt(left, right): + return left < right + +def le(left, right): + return left <= right + +def gt(left, right): + return left > right + +def ge(left, right): + return left >= right + +func_map = { + "==": eq, + "!=": ne, + "< ": lt, + "<=": le, + "> ": gt, + ">=": ge, +} + +compare = [2.0, nan, -nan, inf, -inf] +values = [nan, -nan, inf, -inf] + +for i in range(len(values)): + for j in range(len(compare)): + for op in func_map: + print("%g %s %g -> %s" % + (values[i], op, compare[j], func_map[op](values[i], compare[j]))) + + print("") +@c endfile +@end ignore + @node Ottenere la precisione @subsection Ottenere la precisione voluta diff --git a/doc/wordlist b/doc/wordlist index c93eda53..9ce31188 100644 --- a/doc/wordlist +++ b/doc/wordlist @@ -316,6 +316,7 @@ NR NT NUMCUR NaN +NaNs Nachum Neacsu Neacsu's @@ -483,6 +484,7 @@ VT Versioning Vinschen WIPO +WONTFIX Walamazoo Wallin Watchpoint @@ -25,10 +25,8 @@ */ #include "awk.h" +#include <math.h> -extern double pow(double x, double y); -extern double modf(double x, double *yp); -extern double fmod(double x, double y); NODE **fcall_list = NULL; long fcall_count = 0; int currule = 0; @@ -1521,18 +1519,17 @@ eval_condition(NODE *t) return boolval(t); } -typedef enum { - SCALAR_EQ_NEQ, - SCALAR_RELATIONAL -} scalar_cmp_t; +static bool cmp_doubles(const NODE *t1, const NODE *t2, scalar_cmp_t comparison_type); +extern bool mpg_cmp_as_numbers(const NODE *t1, const NODE *t2, scalar_cmp_t comparison_type); /* cmp_scalars -- compare two nodes on the stack */ -static inline int +static bool cmp_scalars(scalar_cmp_t comparison_type) { NODE *t1, *t2; int di; + bool ret; t2 = POP_SCALAR(); t1 = TOP(); @@ -1540,12 +1537,91 @@ cmp_scalars(scalar_cmp_t comparison_type) DEREF(t2); fatal(_("attempt to use array `%s' in a scalar context"), array_vname(t1)); } - di = cmp_nodes(t1, t2, comparison_type == SCALAR_EQ_NEQ); + + if ((t1->flags & STRING) != 0 || (t2->flags & STRING) != 0) { + bool use_strcmp = (comparison_type == SCALAR_EQ || comparison_type == SCALAR_NEQ); + di = cmp_nodes(t1, t2, use_strcmp); + + switch (comparison_type) { + case SCALAR_EQ: + ret = (di == 0); + break; + case SCALAR_NEQ: + ret = (di != 0); + break; + case SCALAR_LT: + ret = (di < 0); + break; + case SCALAR_LE: + ret = (di <= 0); + break; + case SCALAR_GT: + ret = (di > 0); + break; + case SCALAR_GE: + ret = (di >= 0); + break; + } + } else { + fixtype(t1); + fixtype(t2); + +#ifdef HAVE_MPFR + if (do_mpfr) + ret = mpg_cmp_as_numbers(t1, t2, comparison_type); + else +#endif + ret = cmp_doubles(t1, t2, comparison_type); + } + DEREF(t1); DEREF(t2); - return di; + return ret; } + +/* cmp_doubles --- compare two doubles */ + +static bool +cmp_doubles(const NODE *t1, const NODE *t2, scalar_cmp_t comparison_type) +{ + /* + * This routine provides numeric comparisons that should work + * the same as in C. It should NOT be used for sorting. + */ + + bool t1_nan = isnan(t1->numbr); + bool t2_nan = isnan(t2->numbr); + int ret; + + if ((t1_nan || t2_nan) && comparison_type != SCALAR_NEQ) + return false; + + switch (comparison_type) { + case SCALAR_EQ: + ret = (t1->numbr == t2->numbr); + break; + case SCALAR_NEQ: + ret = (t1->numbr != t2->numbr); + break; + case SCALAR_LT: + ret = (t1->numbr < t2->numbr); + break; + case SCALAR_LE: + ret = (t1->numbr <= t2->numbr); + break; + case SCALAR_GT: + ret = (t1->numbr > t2->numbr); + break; + case SCALAR_GE: + ret = (t1->numbr >= t2->numbr); + break; + } + + return ret; +} + + /* op_assign --- assignment operators excluding = */ static void diff --git a/interpret.h b/interpret.h index 739f81eb..93a50f24 100644 --- a/interpret.h +++ b/interpret.h @@ -486,37 +486,37 @@ uninitialized_scalar: break; case Op_equal: - r = node_Boolean[cmp_scalars(SCALAR_EQ_NEQ) == 0]; + r = node_Boolean[cmp_scalars(SCALAR_EQ)]; UPREF(r); REPLACE(r); break; case Op_notequal: - r = node_Boolean[cmp_scalars(SCALAR_EQ_NEQ) != 0]; + r = node_Boolean[cmp_scalars(SCALAR_NEQ)]; UPREF(r); REPLACE(r); break; case Op_less: - r = node_Boolean[cmp_scalars(SCALAR_RELATIONAL) < 0]; + r = node_Boolean[cmp_scalars(SCALAR_LT)]; UPREF(r); REPLACE(r); break; case Op_greater: - r = node_Boolean[cmp_scalars(SCALAR_RELATIONAL) > 0]; + r = node_Boolean[cmp_scalars(SCALAR_GT)]; UPREF(r); REPLACE(r); break; case Op_leq: - r = node_Boolean[cmp_scalars(SCALAR_RELATIONAL) <= 0]; + r = node_Boolean[cmp_scalars(SCALAR_LE)]; UPREF(r); REPLACE(r); break; case Op_geq: - r = node_Boolean[cmp_scalars(SCALAR_RELATIONAL) >= 0]; + r = node_Boolean[cmp_scalars(SCALAR_GE)]; UPREF(r); REPLACE(r); break; @@ -476,6 +476,50 @@ mpg_cmp(const NODE *t1, const NODE *t2) return cmp_awknums(t1, t2); } +/* mpg_cmp_as_numbers --- compare two numbers, similar to doubles */ + +bool +mpg_cmp_as_numbers(const NODE *t1, const NODE *t2, scalar_cmp_t comparison_type) +{ + /* + * This routine provides numeric comparisons that should work + * the same as in C. It should NOT be used for sorting. + */ + + bool t1_nan = mpfr_nan_p(t1->mpg_numbr); + bool t2_nan = mpfr_nan_p(t2->mpg_numbr); + int ret; + + // MPFR is different than native doubles... + if (t1_nan || t2_nan) + return comparison_type == SCALAR_NEQ; + + int di = mpg_cmp(t1, t2); + + switch (comparison_type) { + case SCALAR_EQ: + ret = (di == 0); + break; + case SCALAR_NEQ: + ret = (di != 0); + break; + case SCALAR_LT: + ret = (di < 0); + break; + case SCALAR_LE: + ret = (di <= 0); + break; + case SCALAR_GT: + ret = (di > 0); + break; + case SCALAR_GE: + ret = (di >= 0); + break; + } + + return ret; +} + /* * mpg_update_var --- update NR or FNR. @@ -370,7 +370,7 @@ int cmp_awknums(const NODE *t1, const NODE *t2) { /* - * This routine is also used to sort numeric array indices or values. + * This routine is used to sort numeric array indices or values. * For the purposes of sorting, NaN is considered greater than * any other value, and all NaN values are considered equivalent and equal. * This isn't in compliance with IEEE standard, but compliance w.r.t. NaN @@ -390,7 +390,6 @@ cmp_awknums(const NODE *t1, const NODE *t2) return 1; } - /* make_str_node --- make a string node */ NODE * |