Actual source code: ex5.c

petsc-master 2017-12-11
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  2: static char help[] = "Tests binary I/O of vectors and illustrates the use of user-defined event logging.\n\n";

  4:  #include <petscvec.h>

  6: /* Note:  Most applications would not read and write a vector within
  7:   the same program.  This example is intended only to demonstrate
  8:   both input and output. */

 10: int main(int argc,char **args)
 11: {
 13:   PetscMPIInt    rank,size;
 14:   PetscInt       i,m = 10,low,high,ldim,iglobal;
 15:   PetscScalar    v;
 16:   Vec            u;
 17:   PetscViewer    viewer;
 18: #if defined(PETSC_USE_LOG)
 19:   PetscLogEvent  VECTOR_GENERATE,VECTOR_READ;
 20: #endif

 22:   PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
 23:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
 24:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 25:   PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);

 27:   /* PART 1:  Generate vector, then write it in binary format */

 29:   PetscLogEventRegister("Generate Vector",VEC_CLASSID,&VECTOR_GENERATE);
 30:   PetscLogEventBegin(VECTOR_GENERATE,0,0,0,0);
 31:   /* Generate vector */
 32:   VecCreate(PETSC_COMM_WORLD,&u);
 33:   VecSetSizes(u,PETSC_DECIDE,m);
 34:   VecSetFromOptions(u);
 35:   VecGetOwnershipRange(u,&low,&high);
 36:   VecGetLocalSize(u,&ldim);
 37:   for (i=0; i<ldim; i++) {
 38:     iglobal = i + low;
 39:     v       = (PetscScalar)(i + 100*rank);
 40:     VecSetValues(u,1,&iglobal,&v,INSERT_VALUES);
 41:   }
 42:   VecAssemblyBegin(u);
 43:   VecAssemblyEnd(u);
 44:   VecView(u,PETSC_VIEWER_STDOUT_WORLD);

 46:   PetscPrintf(PETSC_COMM_WORLD,"writing vector in binary to vector.dat ...\n");
 47:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,"vector.dat",FILE_MODE_WRITE,&viewer);
 48:   VecView(u,viewer);
 49:   PetscViewerDestroy(&viewer);
 50:   VecDestroy(&u);
 51:   PetscOptionsSetValue(NULL,"-viewer_binary_mpiio","");

 53:   PetscLogEventEnd(VECTOR_GENERATE,0,0,0,0);

 55:   /* PART 2:  Read in vector in binary format */

 57:   /* Read new vector in binary format */
 58:   PetscLogEventRegister("Read Vector",VEC_CLASSID,&VECTOR_READ);
 59:   PetscLogEventBegin(VECTOR_READ,0,0,0,0);
 60:   PetscPrintf(PETSC_COMM_WORLD,"reading vector in binary from vector.dat ...\n");
 61:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,"vector.dat",FILE_MODE_READ,&viewer);
 62:   VecCreate(PETSC_COMM_WORLD,&u);
 63:   VecLoad(u,viewer);
 64:   PetscViewerDestroy(&viewer);
 65:   PetscLogEventEnd(VECTOR_READ,0,0,0,0);
 66:   VecView(u,PETSC_VIEWER_STDOUT_WORLD);

 68:   /* Free data structures */
 69:   VecDestroy(&u);
 70:   PetscFinalize();
 71:   return ierr;
 72: }

 74: /*TEST

 76:      test:
 77:        nsize: 1

 79:      test:
 80:        suffix: 2
 81:        nsize: 2

 83: TEST*/