> -snes_test_jacobian -snes_test_jacobian_view
> On Jan 2, 2025, at 5:34 PM, Hammond, Glenn E <glenn.hamm...@pnnl.gov> wrote: > > I need to element info (which row/col combo) to pinpoint which crossterm may > be defective. This is important when debugging analytical derivatives for > chemical reactions. I will look into thr SNES approach. > > Thanks, > > Glenn > >> On Jan 2, 2025, at 2:25 PM, Barry Smith <bsm...@petsc.dev> wrote: >> >> >> Check twice before you click! This email originated from outside PNNL. >> >> >> We also have support for this built into SNES. For example, you provide >> the analytic to SNES which then compute via differencing, mostly to check if >> the analytic implementation was correct. You can run an entire set of >> SNESSolve with this turned on and it will check at all vectors the Jacobian >> is computed how closely the match is (that is it does not just compare the >> two for a single vector). >> >> -snes_test_jacobian <optional threshold> >> >> see the routine SNESTestJacobian() which as the code that compares the >> matrices element by element etc. See also >> https://urldefense.us/v3/__https://petsc.org/release/manual/snes/*checking-accuracy-of-derivatives__;Iw!!G_uCfscf7eWS!epphS19ORHlk58PNC52ioymjvLFv5HFHm_mpJQspG90ykgyw5aaUFtJAkxbYOyhTZ1Jag-BOMLM50u6QJ_9rhhQ$ >> >> >> >> Barry >> >> >> >> >>> On Jan 2, 2025, at 4:51 PM, Stefano Zampini <stefano.zamp...@gmail.com> >>> wrote: >>> >>> MatAXPY for the difference, MatNorm for the relative error >>> >>> >>> On Thu, Jan 2, 2025, 22:32 Hammond, Glenn E via petsc-users >>> <petsc-users@mcs.anl.gov <mailto:petsc-users@mcs.anl.gov>> wrote: >>>> PETSc Users, >>>> >>>> >>>> >>>> I want to compare two Jacobians matrices (one with derivatives calculated >>>> analytically; the other numerically). I want to apply relatives and/or >>>> absolute tolerances. Does anyone know if such capability is built into >>>> PETSc? I cannot find anything other the MatEqual() with compares down to >>>> the bit. Otherwise, I plan to use MatGetValues() and compare the elements >>>> individually. Just hoping there is something more convenient hidden >>>> somewhere. >>>> >>>> >>>> >>>> Thanks, >>>> >>>> >>>> >>>> Glenn >>>> >>
