Perl 5 version 22.4
documentation
cos
- cos
Returns the cosine of EXPR (expressed in radians). If EXPR is omitted,
takes the cosine of $_
.
For the inverse cosine operation, you may use the Math::Trig::acos()
function, or use this relation:
- sub acos { atan2( sqrt(1 - $_[0] * $_[0]), $_[0] ) }