You are viewing the version of this documentation from Perl blead. This is the main development branch of Perl. (git commit c4d03d9396e2ddfe9ecf6e64b31b163698811c1d)
sin EXPR
sin

Returns the sine of EXPR (expressed in radians). If EXPR is omitted, returns sine of $_.

For the inverse sine operation, you may use the Math::Trig::asin function, or use this relation:

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