On the way to solve other error, that problem seems to be solved.
I don’t see that error message anymore.
Because I changed a lot, I cannot reproduce that error, unfortunately.
The modification which seems the most relevant to this error is following.
I used to run torch.svd(A) and torch.symeig(A) with just symmetric matrix A
In modified code, I use torch.svd(A + cI) and torch.symeig(A + cI).
I added some diagonal matrix to have some numerical stability.
I am guessing whether if a matrix has an eigenvalue close to zero then this cause some problem in torch.symeig.
If I have the same problem, I will continue this post with reproduced code.
Thanks!