Aug 29
Trigonometry cheat sheet
This is a rather amateurish Perl cheat sheet for when you're starting with trigonometry in Perl.
First, Perl uses radians instead of degrees, so you'll have to use Math::Trig's rad2deg and deg2rad functions to computer the one or the other, compare Perl Cookbook, ~ chapter 2.
Then you might want to calculate the arcsin of something:
my $deg_alpha = rad2deg(asin($distance_BC * sin(90) / $distance_AB));
asin() from Math::Trig is the function of choice here, but it's not equal to a (non existing) arcsin(), it returns
radians, so you have to send resulting values through rad2deg to get what a dedicated arcsin would have returned.
Another note on tangens: In Math::Trig is a tan() function, but in case you want to code it up by hand, here it is:
sub tan {
my $angle = shift;
return( sin($angle) / cos($angle) );
}