1 2 static char help[] = "Tests MATCENTERING matrix type.\n\n"; 3 4 #include <petscmat.h> 5 6 int main(int argc,char **argv) 7 { 8 PetscInt n; 9 Mat C; 10 Vec x,y; 11 PetscReal norm; 12 PetscMPIInt size; 13 14 CHKERRQ(PetscInitialize(&argc,&argv,(char*)0,help)); 15 CHKERRMPI(MPI_Comm_size(PETSC_COMM_WORLD,&size)); 16 17 /* Create a parallel vector with 10*size total entries, and fill it with 1s. */ 18 n = 10*size; 19 CHKERRQ(VecCreate(PETSC_COMM_WORLD,&x)); 20 CHKERRQ(VecSetSizes(x,PETSC_DECIDE,n)); 21 CHKERRQ(VecSetFromOptions(x)); 22 CHKERRQ(VecSet(x,1.0)); 23 24 /* Create a corresponding n x n centering matrix and use it to create a mean-centered y = C * x. */ 25 CHKERRQ(VecDuplicate(x,&y)); 26 CHKERRQ(MatCreateCentering(PETSC_COMM_WORLD,PETSC_DECIDE,n,&C)); 27 CHKERRQ(MatMult(C,x,y)); 28 29 /* Verify that the centered vector y has norm 0. */ 30 CHKERRQ(VecNorm(y,NORM_2,&norm)); 31 CHKERRQ(PetscPrintf(PETSC_COMM_WORLD,"Vector norm after MatMult() with centering matrix applied to vector of ones is %f.\n",(double)norm)); 32 33 /* Now repeat, but using MatMultTranspose(). */ 34 CHKERRQ(MatMultTranspose(C,x,y)); 35 CHKERRQ(VecNorm(y,NORM_2,&norm)); 36 CHKERRQ(PetscPrintf(PETSC_COMM_WORLD,"Vector norm after MatMultTranspose() with centering matrix applied to vector of ones is %f.\n",(double)norm)); 37 38 /* Clean up. */ 39 CHKERRQ(VecDestroy(&x)); 40 CHKERRQ(VecDestroy(&y)); 41 CHKERRQ(MatDestroy(&C)); 42 CHKERRQ(PetscFinalize()); 43 return 0; 44 } 45 46 /*TEST 47 48 test: 49 suffix: 1 50 nsize: 1 51 output_file: output/ex247.out 52 53 test: 54 suffix: 2 55 nsize: 2 56 output_file: output/ex247.out 57 58 TEST*/ 59