sine and cosine with degree angles
Roberto Ostinelli
<>
Thu Aug 26 13:03:33 CEST 2010
dear list,
sorry if this does sound stupid but i need to compute sine and cosine
of angles expressed in degrees.
the math:sin/1 and math:cos/1 functions compute respectively the sine
and cosine of radiant angles, which can be converted to degrees simply
like this:
radians = degrees * π / 180
however, due to approximations there seem to be an error in the
computation of the cosine of 90° [which should be 0]:
1> math:sin(90 * math:pi() / 180).
1.0
2> math:sin(0 * math:pi() / 180).
0.0
3> math:cos(90 * math:pi() / 180).
6.123233995736766e-17
4> math:cos(0 * math:pi() / 180).
1.0
any suggestions on how to proceed? am i missing some erlang functions on this?
thank you,
r.
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