John Travers <[email protected]> writes: > Hi all, > > I'm trying to use shift and invert to find interior eigenvalues using slepc. > I am using example 4 in slepc 3.41 which reads the matrix from a binary file > ('A' saved from Matlab). > > If I run just: > ./ex4 -file A -eps_nev 1 > the program runs fine, and correctly finds the largest eigenvalue (although > much slower than Matlab's eigs).
You can't compare performance when running in debug mode. If the algorithm converges slower, we can figure out why. > However, if I run: > ./ex4 -file A -eps_nev 1 -st_type sinvert -st_shift 0.0,0.5 > to try and find an eigenvalue near 0.0+0.5i, it outputs the error message > below. Please just insert a value 0.0 along the diagonal of your matrix. MatShift would be more expensive and could hide memory performance bugs if it silently reallocated to add diagonal entries.
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