[petsc-users] Options to set when solving Ax=b if matrix A changes its non-zero position at each solve

[TAY wee-beng]

Hi,

Currently, my matrix A changes its non zero position at each time step.

For e.g.: At a particular node, at time step = 1, I  will insert values 
into its east, west neighbours. At time step = 2, I  will insert values 
into its east, north neighbours. Hence, the non-zero positions at each 
row will be different at each time step. However, the max values per row 
will always be 5 or less.

Currently, after MatSetValues and MatAssemblyBegin/End, I call:

/call MatSetOption(A_mat,MAT_NEW_NONZERO_LOCATIONS,PETSC_TRUE,ierr)

call KSPSetOperators(ksp,A_mat,A_mat,DIFFERENT_NONZERO_PATTERN,ierr)

call KSPGetPC(ksp,pc,ierr)

ksptype=KSPBCGS

call KSPSetType(ksp,ksptype,ierr)

call KSPSetFromOptions(ksp,ierr)

call KSPSolve(ksp,b_rhs,xx,ierr)/

Is this sufficient and correct? If so, apart from KSPSolve, MatSetValues 
and MatAssemblyBegin/End, can I only call the other subroutines once at 
the 1st time step?

Or do I have to explicitly destroy the matrix and create a new one? I 
think I ask this question a while ago but I can't find the email now.

-- 
Yours sincerely,

TAY wee-beng

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