Backsubstitution / forwardsubstitution ONLY

programmer85 — Fri, 05 Mar 2010 14:00:22 GMT

Can anyone write step by step what should be done to do only backsubstitution or only forwardsubstitution ?

I tried to do backward substitution for a (nonsymmetric) SPARSE with nonzeros only in upper part of matrix (no nonzero values below diagonal). For this reason backardsubstitution should be enough.

so I tried to do it as in exapmle of nonsymetric real matrix:

mtype = 11, maxfct = 1; mnum = 1;

(1) PARDISO with phase = 11 (Reordering and Symbolic Factorization)

(2) PARDISO with phase = 22 (factorization)

(3) PARDISO with phase = 333 (backsubstitution only)

(4) PARDISO with phase = -2 (cleaning memoy)

and it did not work ... . When I gave 333 instead of 333 the result was correct.

[1] Shoud I do something more ?? some specyfic settings to use only phase = 333.

[2] What exactly is done in execution with phase = 33 (one backsubstitution and one forwardsubstitution and ... ?)

topic Backsubstitution / forwardsubstitution ONLY in Intel® oneAPI Math Kernel Library

Backsubstitution / forwardsubstitution ONLY