That means that inversion in your ring has been implemented somewhere between Sage 8.9 and Sage 9.4. The simplest and laziest solution is to install 9.4 by compiling from source (not *that* hard). You may also try the 9.2 version, available in Ubuntu 21.04, but I have no idea of the implementation of inverses in your ring in this version...
-- Emmanuel Charpentier Le mardi 5 octobre 2021 à 21:52:25 UTC+2, Samanta a écrit : > Hi supporters, > I am using SageMath (version 8.9) in my Ubuntu 18.04 LTS and during the > calculation of inverse of a matrix in the quotient ring > GF(2)[x]/<x^8+x^2+1>, I am getting an error "NotImplementedError". > However, the determinant of the matrix is a unit in the ring so it is > invertible. Also, I have run the same code in the SageCell ( > https://sagecell.sagemath.org/) and get no error. > I am attaching the details of the error and a picture of the solution from > SageCell. I can't get any idea how to overcome this problem without > installing the latest version of SageMath. Please guide me. > Thanks > > Code: > --------------------------------------------- > R = PolynomialRing(GF(2),'x') > S = R.quotient(x^8 + x^2 + 1,'a') > a = S.gen() > M= matrix([[a,a],[a^2,1]]) > ~M > > Error in SageMath 8.9: > ------------------------------------------- > Traceback (most recent call last): File "<stdin>", line 1, in <module> > File "_sage_input_5.py", line 10, in <module> exec > compile(u'open("___code___.py","w").write("# -*- coding: utf-8 -*-\\n" + > _support_.preparse_worksheet_cell(base64.b64decode("UiA9IFBvbHlub21pYWxSaW5nKEdGKDIpLCd4JykKUyA9IFIucXVvdGllbnQoeF44ICsgeF4yICsgMSkKYSA9IFMuZ2VuKCkKTT0gbWF0cml4KFtbYSxhXSxbYV4yLDFdXSkKfk0="),globals())+"\\n"); > > execfile(os.path.abspath("___code___.py")) File "", line 1, in <module> > File "/tmp/tmpT8yobj/___code___.py", line 7, in <module> exec compile(u'~M > File "", line 1, in <module> File "sage/matrix/matrix0.pyx", line 5389, in > sage.matrix.matrix0.Matrix.__invert__ > (build/cythonized/sage/matrix/matrix0.c:35644) File > "sage/matrix/matrix1.pyx", line 628, in > sage.matrix.matrix1.Matrix.matrix_over_field > (build/cythonized/sage/matrix/matrix1.c:8265) File "sage/rings/ring.pyx", > line 1317, in sage.rings.ring.CommutativeRing.fraction_field > (build/cythonized/sage/rings/ring.c:11715) File "sage/rings/ring.pyx", line > 996, in sage.rings.ring.Ring.is_integral_domain > (build/cythonized/sage/rings/ring.c:8473) NotImplementedError > > Result in SageCell: > ---------------------------------- > [ a^5 + a^3 + a a^6 + a^4 + a^2] > [a^7 + a^5 + a^3 a^6 + a^4 + a^2] > > -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/751a10b2-4286-4bda-9cc6-96d8f44a9e9cn%40googlegroups.com.
