It is very likely that you have not preallocated the matrix. There is a section on this in the manual.
Matt On Sun, Sep 21, 2008 at 1:22 PM, Chen, Changjun <cjchen at math.msu.edu> wrote: > Dear Sir, > I have be using PETSc for many days. Recently I find one subroutine in > PETSc is a little slow, It is an initialization subroutine to fill in the > matrix elements: > > call MatSetValues(A,ione,II,ione,JJ,v,INSERT_VALUES,ierr) > > I find that the total time to fill in the matrix data is even much > longer than the iteration time to solve the system > call KSPSolve(ksp,b,x,ierr) > How could this happen? Could I accelerate the time for filling in the > data? > > Sincerely, > Changjun Chen -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
