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.Fri, 24 May 2013 09:22:04 +0200Sage cannot simplify arccos, but can simplify arcsin?https://ask.sagemath.org/question/10044/sage-cannot-simplify-arccos-but-can-simplify-arcsin/I am using Sage 5.7. It can simplify expressions involving arcsin, but not arccos, why?
Thanks
<pre>
assume(x > 0)
assume(x < pi/2)
acos(cos(x)).simplify_full()
output: arccos(cos(x))
asin(sin(x)).simplify_full()
output: x
</pre>Sat, 20 Apr 2013 18:07:12 +0200https://ask.sagemath.org/question/10044/sage-cannot-simplify-arccos-but-can-simplify-arcsin/Answer by kcrisman for <p>I am using Sage 5.7. It can simplify expressions involving arcsin, but not arccos, why?</p>
<p>Thanks</p>
<pre>assume(x > 0)
assume(x < pi/2)
acos(cos(x)).simplify_full()
output: arccos(cos(x))
asin(sin(x)).simplify_full()
output: x
</pre>
https://ask.sagemath.org/question/10044/sage-cannot-simplify-arccos-but-can-simplify-arcsin/?answer=14813#post-id-14813This is in fact just about Maxima's simplification.
sage: F = asin(sin(x))
sage: F.simplify() # sends to Maxima, nothing else
x
sage: G = acos(cos(x))
sage: G.simplify()
arccos(cos(x))
[This Maxima help thread](http://www.ma.utexas.edu/pipermail/maxima/2011/025117.html) suggests that, as of a couple years ago, this was known but not resolved. I've opened [Maxima bug 2570](https://sourceforge.net/p/maxima/bugs/2570/) for this, though I wouldn't expect immediate response as it may be something somewhat deep in the code that isn't easy to unravel - simplification routines can be notorious for this, I guess.Sat, 20 Apr 2013 23:01:20 +0200https://ask.sagemath.org/question/10044/sage-cannot-simplify-arccos-but-can-simplify-arcsin/?answer=14813#post-id-14813Comment by kcrisman for <p>This is in fact just about Maxima's simplification.</p>
<pre><code>sage: F = asin(sin(x))
sage: F.simplify() # sends to Maxima, nothing else
x
sage: G = acos(cos(x))
sage: G.simplify()
arccos(cos(x))
</code></pre>
<p><a href="http://www.ma.utexas.edu/pipermail/maxima/2011/025117.html">This Maxima help thread</a> suggests that, as of a couple years ago, this was known but not resolved. I've opened <a href="https://sourceforge.net/p/maxima/bugs/2570/">Maxima bug 2570</a> for this, though I wouldn't expect immediate response as it may be something somewhat deep in the code that isn't easy to unravel - simplification routines can be notorious for this, I guess.</p>
https://ask.sagemath.org/question/10044/sage-cannot-simplify-arccos-but-can-simplify-arcsin/?comment=17649#post-id-17649This has now been fixed upstream, and I've opened [Trac 14637](http://trac.sagemath.org/sage_trac/ticket/14637) to add a confirming doctest.Fri, 24 May 2013 09:22:04 +0200https://ask.sagemath.org/question/10044/sage-cannot-simplify-arccos-but-can-simplify-arcsin/?comment=17649#post-id-17649