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diff --git a/doc/gawktexi.in b/doc/gawktexi.in index a7406d62..d2325305 100644 --- a/doc/gawktexi.in +++ b/doc/gawktexi.in @@ -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 +31114,31 @@ 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 |