Doing Trigonometry in Degrees, not Radians
Problem
You want your trigonometry routines to operate in degrees instead of Perl’s native radians.
Solution
Convert between radians and degrees (2π radians equals 360 degrees).
BEGIN {
use constant PI => 3.14159265358979;
sub deg2rad {
my $degrees = shift;
return ($degrees / 180) * PI;
}
sub rad2deg {
my $radians = shift;
return ($radians / PI) * 180;
}
}Alternatively, use the Math::Trig module.
use Math::Trig; $radians = deg2rad($degrees); $degrees = rad2deg($radians);
Discussion
If you’re doing a lot of trigonometry, look into using either
the standard Math::Trig or POSIX modules. They provide many more
trigonometric functions than are defined in the Perl core. Otherwise,
the first solution above will define the
rad2deg
and deg2rad
functions. The value of π isn’t built directly into Perl,
but you can calculate it to as much precision as your floating-point
hardware provides. If you put it in a BEGIN block, this is done at
compile time. In the solution above, the PI
function is a constant created with use
constant.
If you’re looking for the sine in degrees, use this:
# deg2rad and rad2deg defined either as above or from Math::Trig
sub degree_sine {
my $degrees = shift;
my $radians = deg2rad($degrees);
my $result = sin($radians);
return $result;
}See Also
The sin, cos, and
atan2 functions in perlfunc
(1) and Chapter 3 of Programming Perl; the
documentation for the standard POSIX and Math::Trig modules (also in
Chapter 7 of Programming Perl ...