thank you very much! could you please suggest me a robust preconditioner which is independent of the number of processor.
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
