`cos `*EXPR*

This function returns the cosine of

(expressed in radians). For
example, the following script will print a cosine table of angles
measured in degrees:*EXPR*

# Here's the lazy way of getting degrees-to-radians. $pi = atan2(1,1) * 4; $piover180 = $pi/180; # Print table. for ($_ = 0; $_ <= 90; $_++) { printf "%3d %7.5f\n", $_, cos($_ * $piover180); }

For the inverse cosine operation, you may use the `POSIX::acos()`

function, or use this relation:

sub acos { atan2( sqrt(1 - $_[0] * $_[0]), $_[0] ) }