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atan2

atan2 
y
, 
x

Returns the arctangent of y / x in the range -[pi] to [pi]. A quick way to get an approximate value of [pi] is to say:

$pi = atan2(1,1) * 4;
For the tangent operation, you may use the POSIX::tan() function, or use the familiar relation:
sub tan { sin($_[0]) / cos($_[0]) }











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