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Diffstat (limited to 'doc/gawktexi.in')
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1 files changed, 34 insertions, 11 deletions
diff --git a/doc/gawktexi.in b/doc/gawktexi.in index dab833d4..6c4e3b29 100644 --- a/doc/gawktexi.in +++ b/doc/gawktexi.in @@ -59,9 +59,9 @@ @c applies to and all the info about who's publishing this edition @c These apply across the board. -@set UPDATE-MONTH October, 2017 +@set UPDATE-MONTH January, 2018 @set VERSION 4.2 -@set PATCHLEVEL 0 +@set PATCHLEVEL 1 @set GAWKINETTITLE TCP/IP Internetworking with @command{gawk} @ifset FOR_PRINT @@ -279,13 +279,13 @@ Fax: +1-617-542-2652 Email: <email>gnu@@gnu.org</email> URL: <ulink url="https://www.gnu.org">https://www.gnu.org/</ulink></literallayout> -<literallayout class="normal">Copyright © 1989, 1991, 1992, 1993, 1996–2005, 2007, 2009–2017 +<literallayout class="normal">Copyright © 1989, 1991, 1992, 1993, 1996–2005, 2007, 2009–2018 Free Software Foundation, Inc. All Rights Reserved.</literallayout> @end docbook @ifnotdocbook -Copyright @copyright{} 1989, 1991, 1992, 1993, 1996--2005, 2007, 2009--2017 @* +Copyright @copyright{} 1989, 1991, 1992, 1993, 1996--2005, 2007, 2009--2018 @* Free Software Foundation, Inc. @end ifnotdocbook @sp 2 @@ -31041,6 +31041,7 @@ $ @kbd{gawk -M 'BEGIN @{ PREC = 113; printf("%0.25f\n", 1/10) @}'} @node Setting the rounding mode @subsection Setting the Rounding Mode +@cindex @code{ROUNDMODE} variable The @code{ROUNDMODE} variable provides program-level control over the rounding mode. The correspondence between @code{ROUNDMODE} and the IEEE @@ -31113,6 +31114,32 @@ distributes upward and downward rounds of exact halves, which might cause any accumulating round-off error to cancel itself out. This is the default rounding mode for IEEE 754 computing functions and operators. +@c January 2018. Thanks to nethox@gmail.com for the example. +@sidebar Rounding Modes and Conversion +It's important to understand that, along with @code{CONVFMT} and +@code{OFMT}, the rounding mode affects how numbers are converted to strings. +For example, consider the following program: + +@example +BEGIN @{ + pi = 3.1416 + OFMT = "%.f" # Print value as integer + print pi # ROUNDMODE = "N" by default. + ROUNDMODE = "U" # Now change ROUNDMODE + print pi +@} +@end example + +@noindent +Running this program produces this output: + +@example +$ @kbd{gawk -M -f roundmode.awk} +@print{} 3 +@print{} 4 +@end example +@end sidebar + The other rounding modes are rarely used. Rounding toward positive infinity (@code{roundTowardPositive}) and toward negative infinity (@code{roundTowardNegative}) are often used to implement interval @@ -31411,11 +31438,14 @@ BEGIN @{ if (! adequate_math_precision(fpbits)) @{ print("Error: insufficient computation precision available.\n" \ "Try again with the -M argument?") > "/dev/stderr" + # Note: you may need to set a flag here to bail out of END rules exit 1 @} @} @end example +Please be aware that @code{exit} will jump to the @code{END} rules, if present (@pxref{Exit Statement}). + @node POSIX Floating Point Problems @section Standards Versus Existing Practice @@ -39349,13 +39379,6 @@ The people maintaining the various @command{gawk} ports are: If your bug is also reproducible under Unix, send a copy of your report to the @EMAIL{bug-gawk@@gnu.org,bug-gawk at gnu dot org} email list as well. -@c 7/2017, Juan Guerrero has taken over the DJGPP port. -@ignore -The DJGPP port is no longer supported; it will remain in the code base -for a while in case a volunteer wishes to take it over. If this does -not happen, then eventually code for this port will be removed. -@end ignore - @node Other Versions @appendixsec Other Freely Available @command{awk} Implementations @cindex @command{awk}, implementations |