Closed edd8e884-f507-429a-b577-5d554626c0fe closed 8 years ago
Same with sin(pi+pi/42)
.
I do not have intermediate versions of Sage with me, but i confirm that it is a regression since on Sage 5.12, we have:
sage: cos(pi+pi*1/42)
cos(43/42*pi)
sage: sin(pi+pi/42)
sin(43/42*pi)
No, the changes were just a few months ago, will get to it tomorrow.
More precisely, on a 7.2.beta4 version of Sage which i can reach by ssh, it works well:
sage: cos(pi+pi*1/42)
cos(43/42*pi)
sage: sin(pi+pi*1/42)
sin(43/42*pi)
So the regression is very recent, could it be due to the last update of pynac/ginac ?
Description changed:
---
+++
@@ -1,4 +1,4 @@
-As reported in [this ask question](http://ask.sagemath.org/question/33623/bug-in-cos-function-in-version-72/?answer=33624#post-id-33624), Sage makes wrong simplifications in symbolic trigonometry:
+As reported in [this ask question](http://ask.sagemath.org/question/33623/bug-in-cos-function-in-version-72/?answer=33624#post-id-33624), Sage makes wrong simplifications in symbolic trigonometry involving fractions:
sage: cos(pi+pi*1/42)
So the regression is very recent, could it be due to the last update of pynac/ginac ?
Almost certainly so. See e.g. this bug, though I assume it is a different particular one.
This is fixed and doctested in #20742.
Determined to be invalid/duplicate/wontfix (closing as "wontfix" as a catch-all resolution).
As reported in this ask question, Sage makes wrong simplifications in symbolic trigonometry involving fractions:
While it should be
-cos(1/42*pi)
.CC: @rwst
Component: symbolics
Issue created by migration from https://trac.sagemath.org/ticket/20752