You are viewing the version of this documentation from Perl blead. This is the main development branch of Perl. (git commit a980fe3248276810495858e3d34c7d140e09e852)
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])) }