[petsc-users] about speed

[Xuan YU]

Hi,

I am using TS solving a nonlinear problem. I created an approximate  
data structure for Jacobian matrix to be used with matcoloring, my  
MatFDColoringView is like this:
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But the speed of code is too slow than what I expected. Only 10 time  
step costs 11seconds!

What's wrong with my code? How can I speed up?

Thanks!

This is the ts_view result.

TS Object:
   type: beuler
   maximum steps=100
   maximum time=10
   total number of nonlinear solver iterations=186
   total number of linear solver iterations=423
   SNES Object:
     type: ls
       line search variant: SNESLineSearchCubic
       alpha=0.0001, maxstep=1e+08, minlambda=1e-12
     maximum iterations=50, maximum function evaluations=10000
     tolerances: relative=1e-08, absolute=1e-50, solution=1e-08
     total number of linear solver iterations=1
     total number of function evaluations=19
     KSP Object:
       type: gmres
         GMRES: restart=30, using Classical (unmodified) Gram-Schmidt  
Orthogonalization with no iterative refinement
         GMRES: happy breakdown tolerance 1e-30
       maximum iterations=10000, initial guess is zero
       tolerances:  relative=1e-05, absolute=1e-50, divergence=10000
       left preconditioning
       using PRECONDITIONED norm type for convergence test
     PC Object:
       type: ilu
         ILU: out-of-place factorization
         0 levels of fill
         tolerance for zero pivot 1e-12
         using diagonal shift to prevent zero pivot
         matrix ordering: natural
         factor fill ratio given 1, needed 1
           Factored matrix follows:
             Matrix Object:
               type=seqaij, rows=1838, cols=1838
               package used to perform factorization: petsc
               total: nonzeros=8464, allocated nonzeros=8464
               total number of mallocs used during MatSetValues calls =0
                 not using I-node routines
       linear system matrix = precond matrix:
       Matrix Object:
         type=seqaij, rows=1838, cols=1838
         total: nonzeros=8464, allocated nonzeros=9745
         total number of mallocs used during MatSetValues calls =37
           not using I-node routines


Xuan YU
xxy113 at psu.edu