View Full Version : Final Summary: Calculation of 2D Angles ('CAST' problem)

Dr. Chris Kirtley
01-03-2003, 02:46 AM
Happy new year to all.

Before I forget, I want to thank everyone who replied about the 2D angle
calculation problem. I have collated all the responses here:


With the risk of offending everyone else, I am going to give my prize to
Zia Hasan, who came up with the following very simple algorithm:

IF x not equal to zero THEN angle = ATN(y/x) ELSE angle = SGN(y) * pi /
IF x < 0 THEN angle = angle + pi
IF angle < 0 THEN angle = angle +2*pi

I have checked this out for angles from 0 to 315 in steps of 45 degrees
in this little Excel spreadsheet:

As you can see, it works nicely. This might be a nice addition to the
ISB Software Archive.

Thanks again to everyone, and especially to Zia!

Dr. Chris Kirtley MD PhD
Associate Professor
Dept. of Biomedical Engineering
Catholic University of America
620 Michigan Ave NE, Washington, DC 20064
Tel. 202-319-6247, fax 202-319-4287
Email: kirtley@cua.edu

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