Calculating More Trigonometric Functions

Problem

You want to calculate values for trigonometric functions like sine, tangent, or arc-cosine.

Solution

Perl provides only sin, cos, and atan2 as standard functions. From these, you can derive tan and the other trig functions:

sub tan {
 my $theta = shift;
return sin($theta)/cos($theta);
}

The POSIX module provides a wider range of trig functions:

use POSIX; $y = acos(3.7);

The Math::Trig module provides a complete set of functions and supports operations on or resulting in complex numbers:

use Math::Trig; $y = acos(3.7);

The tan function will cause a division-by-zero exception when $theta is and so on, because the cosine is 0 for these values. Similarly, tan and many other functions from Math::Trig may generate the same error. To trap these, use eval:

eval {
 $y = tan($pi/2);
}
or return undef;