Re: Calculation of 2D Angles ('CAST' problem)

[Ulrich Simon]

Dear Dr. Kirtley,

Are you able to use the ATAN2 Function? The ATAN2 function is
implemented in most of the standard program languages (C, MatLab,
FORTRAN, &). This function is called with two arguments instead of only
one argument.
Use: alpha = ATAN2(Y, X) in the range ( Pi < alpha < Pi)
Instead of: alpha = ATAN(Z); Z = Y/X in the range ( Pi/2 < alpha < Pi/2)
However, internally the ATAN2 function does nothing else than your self
written tool: determining the particular quadrant from the signs of the
two arguments. There is definitely no other way to calculate it.

Best regards
Ulrich Simon

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Dr.-Ing. Ulrich Simon
Institute of Orthopaedic Research and Biomechanics
University of Ulm
www.biomechanics.de
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