ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sun, 11 Jul 2021 11:38:02 +0200Simplification of arctan2(f1,f2) expressions.https://ask.sagemath.org/question/57939/simplification-of-arctan2f1f2-expressions/Why doesn't `arctan2(sqrt(a^2 + r^2)*sin(phi)*sin(th), sqrt(a^2 + r^2)*cos(phi)*sin(th))` simplify to phi or at least `arctan2(sin(phi),cos(phi))`?Fri, 09 Jul 2021 16:35:33 +0200https://ask.sagemath.org/question/57939/simplification-of-arctan2f1f2-expressions/Comment by AlanTStafford for <p>Why doesn't <code>arctan2(sqrt(a^2 + r^2)*sin(phi)*sin(th), sqrt(a^2 + r^2)*cos(phi)*sin(th))</code> simplify to phi or at least <code>arctan2(sin(phi),cos(phi))</code>?</p>
https://ask.sagemath.org/question/57939/simplification-of-arctan2f1f2-expressions/?comment=57960#post-id-57960I was working out transformations between coordinate systems. As a test I transformed and then untransformed so there should be no change. However I get this term which won't simplify back to phi.Sun, 11 Jul 2021 11:38:02 +0200https://ask.sagemath.org/question/57939/simplification-of-arctan2f1f2-expressions/?comment=57960#post-id-57960Comment by Emmanuel Charpentier for <p>Why doesn't <code>arctan2(sqrt(a^2 + r^2)*sin(phi)*sin(th), sqrt(a^2 + r^2)*cos(phi)*sin(th))</code> simplify to phi or at least <code>arctan2(sin(phi),cos(phi))</code>?</p>
https://ask.sagemath.org/question/57939/simplification-of-arctan2f1f2-expressions/?comment=57959#post-id-57959Why should it ?Sun, 11 Jul 2021 09:01:53 +0200https://ask.sagemath.org/question/57939/simplification-of-arctan2f1f2-expressions/?comment=57959#post-id-57959