Actual source code: ex1.c

petsc-3.7.1 2016-05-15
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  2: static char help[] = "Tests solving linear system on 0 by 0 matrix.\n\n";

  4: #include <petscksp.h>

  8: int main(int argc,char **args)
  9: {
 10:   Mat            C;
 12:   PetscInt       N = 0;
 13:   Vec            u,b,x;
 14:   KSP            ksp;
 15:   PetscReal      norm;

 17:   PetscInitialize(&argc,&args,(char*)0,help);

 19:   /* create stiffness matrix */
 20:   MatCreate(PETSC_COMM_WORLD,&C);
 21:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,N,N);
 22:   MatSetFromOptions(C);
 23:   MatSetUp(C);
 24:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 25:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

 27:   /* create right hand side and solution */
 28:   VecCreate(PETSC_COMM_WORLD,&u);
 29:   VecSetSizes(u,PETSC_DECIDE,N);
 30:   VecSetFromOptions(u);
 31:   VecDuplicate(u,&b);
 32:   VecDuplicate(u,&x);
 33:   VecSet(u,0.0);
 34:   VecSet(b,0.0);

 36:   VecAssemblyBegin(b);
 37:   VecAssemblyEnd(b);


 40:   /* solve linear system */
 41:   KSPCreate(PETSC_COMM_WORLD,&ksp);
 42:   KSPSetOperators(ksp,C,C);
 43:   KSPSetFromOptions(ksp);
 44:   KSPSolve(ksp,b,u);

 46:   MatMult(C,u,x);
 47:   VecAXPY(x,-1.0,b);
 48:   VecNorm(x,NORM_2,&norm);

 50:   KSPDestroy(&ksp);
 51:   VecDestroy(&u);
 52:   VecDestroy(&x);
 53:   VecDestroy(&b);
 54:   MatDestroy(&C);
 55:   PetscFinalize();
 56:   return 0;
 57: }