On Fri, Aug 16, 2013 at 7:32 AM, 丁老师 <[email protected]> wrote:
> thank you very much! could you please suggest me a robust preconditioner > which is independent of the number of processor. > For generic problems, they do not exist. I suggest looking in the literature for your specific problem, and then trying to construct the best few choices in PETSc. Matt > > 在 2013-08-16 19:54:01，"Matthew Knepley" <[email protected]> 写道： > > On Fri, Aug 16, 2013 at 6:13 AM, 丁老师 <[email protected]> wrote: > > Its common for iterative solvers to converge differently for different PC. > You are using block Jacobi-ILU > which is different for different numbers of processes. > > Matt > > /* Program usage: mpiexec ex1 [-help] [all PETSc options] */ >> >> static char help[] = "Basic vector routines.\n\n"; >> >> >> #include "petscksp.h" >> #include "petscvec.h" >> >> >> >> int main(int argc,char **argv) >> { >> int N=16; >> >> int MyRank; >> >> Mat A; >> PC Pc; >> KSP ksp; >> Vec b,x; >> >> PetscInitialize(&argc,&argv,(char*)0,help); >> MPI_Comm_rank(MPI_COMM_WORLD,&MyRank); >> >> MatCreate(PETSC_COMM_WORLD,&A); >> MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N); >> MatSetFromOptions(A); >> MatMPIAIJSetPreallocation(A,5,PETSC_NULL,5,PETSC_NULL); >> >> VecCreate(PETSC_COMM_WORLD,&b); >> VecSetSizes(b,PETSC_DECIDE,N); >> VecSetFromOptions(b); >> VecDuplicate(b,&x); >> &n bsp; >> int row=0; >> int* col3; >> int* col4; >> int* col5; >> PetscMalloc(3*sizeof(PetscInt),&col3); >> PetscMalloc(4*sizeof(PetscInt),&col4); >> PetscMalloc(5*sizeof(PetscInt),&col5); >> >> col3[0]=0; col3[1]=1; col3[2]=4; >> double >> value3[3]={2.2916666666666665e+00,-1.1458333333333333e+00,-1.1458333333333333e+00}; >> MatSetValues(A,1,&row,3,col3,value3,INSERT_VALUES); >> >> row=1; >> col4[0]=0; col4[1]=1; col4[2]=2; col4[3]=5; >> double >> value4[4]={-1.1458333333333333e+00,3.8020833333333330e+00,-1.2500000000000000e+00 >> ,-1.4062500000000000e+00}; >> MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES); >> >> >> row=2; >> col4[0]=1; col4[1]=2; col4[2]=3; col4[3]=6; >> value4[0]=-1.2500000000000000e+00; >> value4[1]=3.8020833333333330e+00; >> value4[2]=-1.1458333333333333e+00 ; >> &n bsp;value4[3]=-1.4062500000000000e+00; >> MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES); >> >> >> row=3; >> col3[0]=2; col3[1]=3; col3[2]=7; >> value3[0]=-1.1458333333333333e+00; >> value3[1]=2.2916666666666665e+00; >> value3[2]=-1.1458333333333333e+00; >> MatSetValues(A,1,&row,3,col3,value3,INSERT_VALUES); >> >> >> row=4; >> col4[0]=0; col4[1]=4; col4[2]=5; col4[3]=8; >> value4[0]=-1.1458333333333333e+00; >> value4[1]=3.8020833333333330e+00; >> value4[2]=-1.4062500000000000e+00; >> value4[3]=-1.2500000000000000e+00; >> MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES); >> >> row=5; >> col5[0]=1; col5[1]=4; col5[2]=5; col5[3]=6; col5[4]=9; >> double value5[5]; >> value5[0]=-1.4062500000000000e+00; >> value5[1]=-1.4062500000000000e+00; >> value5[2]=5 .9375000000000000e+00; >> value5[3]=-1.5625000000000000e+00 ; >> value5[4]=-1.5625000000000000e+00 ; >> MatSetValues(A,1,&row,5,col5,value5,INSERT_VALUES); >> >> >> >> row=6; >> col5[0]=2; col5[1]=5; col5[2]=6; col5[3]=7; col5[4]=10; >> value5[0]=-1.4062500000000000e+00; >> value5[1]=-1.5625000000000000e+00; >> value5[2]=5.9375000000000000e+00; >> value5[3]=-1.4062500000000000e+00 ; >> value5[4]=-1.5625000000000000e+00 ; >> MatSetValues(A,1,&row,5,col5,value5,INSERT_VALUES); >> >> row=7; >> col4[0]=3; col4[1]=6; col4[2]=7; col4[3]=11; >> value4[0]=-1.1458333333333333e+00; >> value4[1]=-1.4062500000000000e+00; >> value4[2]=3.8020833333333330e+00; >> value4[3]=-1.2500000000000000e+00; >> MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES); >> >> row=8; >> col4[0]=4; col4[1]=8; col4[2]=9; col4[3]=12; >> value4[0]=-1.2500000000000000e+00; >> value4[1]=3.8020833333333330e+00; >> value4[2]=-1.4062500000000000e+00; >> value4[3]=-1.1458333333333333e+00; >> MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES); >> >> >> row=9; >> col5[0]=5; col5[1]=8; col5[2]=9; col5[3]=10; col5[4]=13; >> value5[0]=-1.5625000000000000e+00; >> value5[1]=-1.4062500000000000e+00; >> value5[2]=5.9375000000000000e+00; >> value5[3]=-1.5625000000000000e+00 ; >> value5[4]= -1.4062500000000000e+00; >> MatSetValues(A,1,&row,5,col5,value5,INSERT_VALUES); >> >> row=10; >> col5[0]=6; col5[1]=9; col5[2]=10; col5[3]=11; col5[4]=14; >> value5[0]=-1.5625000000000000e+00; >> value5[1]=-1.5625000000000000e+00; >> value5[2]=5.93750000000000 00e+00; >> value5[3]=-1.4062500000000000e+00 ; >> value5[4]= -1.4062500000000000e+00; >> MatSetValues(A,1,&row,5,col5,value5,INSERT_VALUES); >> >> >> row=11; >> col4[0]=7; col4[1]=10; col4[2]=11; col4[3]=15; >> value4[0]=-1.2500000000000000e+00; >> value4[1]=-1.4062500000000000e+00; >> value4[2]=3.8020833333333330e+00; >> value4[3]=-1.1458333333333333e+00; >> MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES); >> >> >> >> >> row=12; >> col3[0]=8; col3[1]=12; col3[2]=13; >> value3[0]=-1.1458333333333333e+00; >> value3[1]=2.2916666666666665e+00; >> value3[2]=-1.1458333333333333e+00; >> MatSetValues(A,1,&row,3,col3,value3,INSERT_VALUES); >> >> >> row=13; >> col4[0]=9; col4[1]=12; col4[2]=13; col4[3]= 14; >> value4[0]=-1.4062500000000000e+00; >> value4[1]=-1.1458333333333333e+00; >> value4[2]=3.8020833333333330e+00; >> value4[3]=-1.2500000000000000e+00; >> MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES); >> >> >> row=14; >> col4[0]=10; col4[1]=13; col4[2]=14; col4[3]=15; >> value4[0]=-1.4062500000000000e+00; >> value4[1]=-1.2500000000000000e+00; >> value4[2]=3.8020833333333330e+00; >> value4[3]=-1.1458333333333333e+00; >> MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES); >> >> >> >> row=15; >> col3[0]=11; col3[1]=14; col3[2]=15; >> value3[0]=-1.1458333333333333e+00; >> value3[1]=-1.1458333333333333e+00; >> value3[2]=2.2916666666666665e+00; >> MatSetValues(A,1,&row,3,col3,value3,INSERT_VALUES); >> >> >> &n bsp; >> MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY); >> MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY); >> >> // MatView(A,PETSC_VIEWER_STDOUT_WORLD); >> >> >> >> double val[16]={-7.6233779415782715e-04, >> -3.0457072596705860e-04, >> 3.0457072596705860e-04, >> 7.6233779415782715e-04, >> -4.4764543813290442e-03, >> -1.6196451741044846e-03, >> 1.6196451741044846e-03, >> 4.4764543813290442e-03, >> -1.9333475373837013e-02, >> -5.4815619458573189e-03, >> 5.4815619458573189e-03, >> 1.9333475373837013e-02, >> -8.4153777598326651e-02, >> -1.2883385353962010e-02, >> 1.2883385353962010e-02, >> 8.4153777598326651e-02}; >> >> int* col16; >> PetscMalloc(16*sizeof(PetscInt),&col16); >> for(int i=0;i<16;i++) >> col16[i]=i; >> >> VecSetValues(b,16,col16,val,INSERT_VALUES); >> VecAssemblyBegin(b); >> VecAssemblyEnd(b); >> // >> &nbs p; VecView(b,PETSC_VIEWER_STDOUT_WORLD); >> >> >> KSPCreate(PETSC_COMM_WORLD,&ksp); >> KSPSetOperators(ksp,A,A,SAME_NONZERO_PATTERN); >> KSPSetOperators(ksp,A,A,SAME_PRECONDITIONER); >> KSPSetInitialGuessNonzero(ksp,PETSC_FALSE); >> >> KSPSetType(ksp,KSPBCGS); >> // KSPSetType(ksp,KSPLSQR); >> // KSPSetType(ksp,KSPFGMRES); >> // KSPSetType(ksp,KSPDGMRES); >> //KSPSetType(ksp,KSPTCQMR); >> // KSPSetType(ksp,KSPPREONLY); >> >> //KSPGetPC(ksp,&Pc); >> // PCSetType(Pc,PCJACOBI); >> KSPSetFromOptions(ksp); >> KSPSetTolerances(ksp,1.e-20,1.e-20,PETSC_DEFAULT,1000); >> KSPSolve(ksp,b,x); >> >> >> VecView(x,PETSC_VIEWER_STDOUT_WORLD); >> >> >> PetscFinalize(); >> return 0; >> } >> >> >> >> >> > > > -- > 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 > > > > -- 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
