gawk: MPFR features

1 
1 15.3 Arbitrary-Precision Arithmetic Features in 'gawk'
1 ======================================================
1 
1 By default, 'gawk' uses the double-precision floating-point values
1 supplied by the hardware of the system it runs on.  However, if it was
1 compiled to do so, and the '-M' command-line option is supplied, 'gawk'
1 uses the GNU MPFR (http://www.mpfr.org) and GNU MP (https://gmplib.org)
1 (GMP) libraries for arbitrary-precision arithmetic on numbers.  You can
1 see if MPFR support is available like so:
1 
1      $ gawk --version
1      -| GNU Awk 4.1.2, API: 1.1 (GNU MPFR 3.1.0-p3, GNU MP 5.0.2)
1      -| Copyright (C) 1989, 1991-2015 Free Software Foundation.
1      ...
1 
1 (You may see different version numbers than what's shown here.  That's
1 OK; what's important is to see that GNU MPFR and GNU MP are listed in
1 the output.)
1 
1    Additionally, there are a few elements available in the 'PROCINFO'
11 array to provide information about the MPFR and GMP libraries (⇒
 Auto-set).
1 
1    The MPFR library provides precise control over precisions and
1 rounding modes, and gives correctly rounded, reproducible,
1 platform-independent results.  With the '-M' command-line option, all
1 floating-point arithmetic operators and numeric functions can yield
1 results to any desired precision level supported by MPFR.
1 
1    Two predefined variables, 'PREC' and 'ROUNDMODE', provide control
1 over the working precision and the rounding mode.  The precision and the
1 Setting precision:: and ⇒Setting the rounding mode for more
1 information.
1