Consecutive identical eigenproblems give different results

Open CluelessGuru opened this issue 5 years ago • 2 comments

Expected behavior

If 2 identical consecutive eigenproblems are solved the results should be identical

Actual behavior

They are not because the lapack random number generator is initialized only once for the first eigenproblem and never again. Hence the starting vector for the 2 identical consecutive eigenproblems are not the same and the final result differes.

Where/how to reproduce the problem

arpack-ng: release
OS: ubuntu
compiler: gcc

Steps to reproduce the problem

Solve 2 identical consecutive eigenvalue problems.

Oct 05 '20 15:10 CluelessGuru

No solution for now. Duplicate : https://github.com/opencollab/arpack-ng/issues/218

Oct 06 '20 21:10 fghoussen

and the final result differes.

BTW, how much in norm for instance? 1.e-6 in double? 1.e-3 in float? more?

Oct 23 '22 10:10 fghoussen