Hi, I have a performance issue while trying to insert values in the a matrix. I am using DMMG solver for cell-centered scheme in 3D from the petsc-snapshot to solve a Poisson equations. Inserting coefficients in the matrix for dirichlet or neumann boundary conditions, the insertion is instantaneous. But is I want to insert coefficients for periodic boundary conditions, I can notice a huge slow down in the insertion process (not in the resolution though). The smallest size I can notice the performance drop is 32*32*32.
Is there any way to improve this? col.i = row.i+(mx-1); col.j = row.j; col.k = row.k; v[0] = 1; MatSetValuesStencil(*A,1,&row,1,&col,v,ADD_VALUES); Thans, Christophe
