13.3.1 Constants

Submitted by admin on Fri, 2007-11-16 11:12

13.3.1  Constants

The Math::Cephes gives access to a set of frequently used constants in scientific computation such as p, , , , , , ln 2, , etc. The following program simply prints out the values of some such constants. The constants can be either imported individually, or as a group, using the keyword :constants.

 Program 13.2


#!/usr/bin/perl
#file const.pl

use Math::Cephes qw(:constants);
print "PI = " . $Math::Cephes::PI . "\n";
print "PI over 2 = " . $Math::Cephes::PIO2 . "\n";
print "PI over 4 = " . $Math::Cephes::PIO4 . "\n";
print "SQRT of 2 = " . $Math::Cephes::SQRT2 . "\n";
print "SQRT of 2 over PI  = " . $Math::Cephes::SQ2OPI . "\n";
print "2 over PI  = " . $Math::Cephes::TWOOPI . "\n";
print "LOG to base E  of 2 = " . $Math::Cephes::LOGE2 . "\n";
print "1 over LOG to base E  of 2 = " . $Math::Cephes::LOG2E . "\n";
print "Machine Roundoff Error = " . $Math::Cephes::MACHEP . "\n";
print "Maximum log on the machine = " . $Math::Cephes::MAXLOG . "\n";
print "Minimum log on the machine  = " . $Math::Cephes::MINLOG . "\n";
print "Maximum number on the machine = " . $Math::Cephes::MAXNUM . "\n";

The output of the program is mostly self-explanatory. The bottom of the program prints out certain machine-dependent constants that are useful for performing certain mathematical computation. 

PI = 3.14159265358979

PI over 2 = 1.5707963267949

PI over 4 = 0.785398163397448

SQRT of 2 = 1.4142135623731

SQRT of 2 over PI  = 0.797884560802865

2 over PI  = 0.636619772367581

LOG to base E  of 2 = 0.693147180559945

1 over LOG to base E  of 2 = 1.44269504088896

Machine Roundoff Error = 1.11022302462516e-16

Maximum log on the machine = 709.782712893384

Minimum log on the machine  = -745.133219101941

Maximum number on the machine = 1.79769313486232e+308