Symbolic matrix inversion broken?
The result of the following is a bit unexpected.
sage: n=3;
sage: D = matrix.diagonal(SR,(var(f'd_{i+1}',domain='real') for i in range(n)))
sage: D
[d_1 0 0]
[ 0 d_2 0]
[ 0 0 d_3]
sage: D.inverse()
[1 0 0]
[0 1 0]
[0 0 1]Clearly, that's generally not the inverse. The inverse()-method should either produce 1/di on the diagonal or throw an exception that perhaps it cannot divide by the di because they might be zero. That I'd understand. But why the 1s?
What is your SageMath version? https://sagecell.sagemath.org/ gives the right answer.
Sagecell is running 10.1. This also works for me in sage 10.2.beta9.
Good point.
sage0_versionsays "'SageMath version 10.0, Release Date: 2023-05-20'". I'll update and report back.It works for me after updating SageMath from 10.0 to 10.1 via Homebrew. I still have no clue why this didn't work in 10.0 on my two machines (both Mac, one Apple-Silicon, one Intel, both SM10.0). I'll leave the question open for a bit in case someone can offer an explanation.
Because this has been fixed recently. You can close your question.