ASKSAGE: Sage Q&A Forum - Latest question feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sat, 06 Oct 2018 01:04:49 -0500Characteristic polynomial of symbolic matrix of size 7https://ask.sagemath.org/question/43839/characteristic-polynomial-of-symbolic-matrix-of-size-7/There is a problem when computing the characteristic polynomial of a matrix of size greater than 7 containing a large number of symbolic variables.
<pre><code>a = SR.var('a', 100)
M = identity_matrix(SR, 7)
for i in range(7):
for j in range(7):
M[i,j] = a[i*7+j]
print(M.charpoly().degree()) # prints 5
</code></pre>
The value it should print is 7. Over $\mathbb{Z}[a_0,a_1,\dots]$, the result is correct.
I use Sage 8.3 (Release Date: 2018-08-03), installed from the official repository of Archlinux. The bug is present both in command line and with `sage file.sage` (if I copy and paste the code above).ScreenNameSat, 06 Oct 2018 01:04:49 -0500https://ask.sagemath.org/question/43839/