Actual source code: vecmpitoseq.c
petsc-3.7.1 2016-05-15
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      2: #include <petsc/private/vecimpl.h>    /*I   "petscvec.h"    I*/

      6: /*@
      7:       VecScatterCreateToAll - Creates a vector and a scatter context that copies all
      8:           vector values to each processor

     10:   Collective on Vec

     12:   Input Parameter:
     13: .  vin  - input MPIVEC

     15:   Output Parameter:
     16: +  ctx - scatter context
     17: -  vout - output SEQVEC that is large enough to scatter into

     19:   Level: intermediate

     21:    Note: vout may be NULL [NULL_OBJECT from fortran] if you do not
     22:    need to have it created

     24:    Usage:
     25: $        VecScatterCreateToAll(vin,&ctx,&vout);
     26: $
     27: $        // scatter as many times as you need
     28: $        VecScatterBegin(ctx,vin,vout,INSERT_VALUES,SCATTER_FORWARD);
     29: $        VecScatterEnd(ctx,vin,vout,INSERT_VALUES,SCATTER_FORWARD);
     30: $
     31: $        // destroy scatter context and local vector when no longer needed
     32: $        VecScatterDestroy(&ctx);
     33: $        VecDestroy(&vout);

     35:     Do NOT create a vector and then pass it in as the final argument vout! vout is created by this routine
     36:   automatically (unless you pass NULL in for that argument if you do not need it).

     38: .seealso VecScatterCreate(), VecScatterCreateToZero(), VecScatterBegin(), VecScatterEnd()

     40: @*/
     41: PetscErrorCode  VecScatterCreateToAll(Vec vin,VecScatter *ctx,Vec *vout)
     42: {

     45:   PetscInt       N;
     46:   IS             is;
     47:   Vec            tmp;
     48:   Vec            *tmpv;
     49:   PetscBool      tmpvout = PETSC_FALSE;

     55:   if (vout) {
     57:     tmpv = vout;
     58:   } else {
     59:     tmpvout = PETSC_TRUE;
     60:     tmpv    = &tmp;
     61:   }

     63:   /* Create seq vec on each proc, with the same size of the original mpi vec */
     64:   VecGetSize(vin,&N);
     65:   VecCreateSeq(PETSC_COMM_SELF,N,tmpv);
     66:   /* Create the VecScatter ctx with the communication info */
     67:   ISCreateStride(PETSC_COMM_SELF,N,0,1,&is);
     68:   VecScatterCreate(vin,is,*tmpv,is,ctx);
     69:   ISDestroy(&is);
     70:   if (tmpvout) {VecDestroy(tmpv);}
     71:   return(0);
     72: }

     77: /*@
     78:       VecScatterCreateToZero - Creates an output vector and a scatter context used to
     79:               copy all vector values into the output vector on the zeroth processor

     81:   Collective on Vec

     83:   Input Parameter:
     84: .  vin  - input MPIVEC

     86:   Output Parameter:
     87: +  ctx - scatter context
     88: -  vout - output SEQVEC that is large enough to scatter into on processor 0 and
     89:           of length zero on all other processors

     91:   Level: intermediate

     93:    Note: vout may be NULL [NULL_OBJECT from fortran] if you do not
     94:    need to have it created

     96:    Usage:
     97: $        VecScatterCreateToZero(vin,&ctx,&vout);
     98: $
     99: $        // scatter as many times as you need
    100: $        VecScatterBegin(ctx,vin,vout,INSERT_VALUES,SCATTER_FORWARD);
    101: $        VecScatterEnd(ctx,vin,vout,INSERT_VALUES,SCATTER_FORWARD);
    102: $
    103: $        // destroy scatter context and local vector when no longer needed
    104: $        VecScatterDestroy(&ctx);
    105: $        VecDestroy(&vout);

    107: .seealso VecScatterCreate(), VecScatterCreateToAll(), VecScatterBegin(), VecScatterEnd()

    109:     Do NOT create a vector and then pass it in as the final argument vout! vout is created by this routine
    110:   automatically (unless you pass NULL in for that argument if you do not need it).

    112: @*/
    113: PetscErrorCode  VecScatterCreateToZero(Vec vin,VecScatter *ctx,Vec *vout)
    114: {

    117:   PetscInt       N;
    118:   PetscMPIInt    rank;
    119:   IS             is;
    120:   Vec            tmp;
    121:   Vec            *tmpv;
    122:   PetscBool      tmpvout = PETSC_FALSE;

    128:   if (vout) {
    130:     tmpv = vout;
    131:   } else {
    132:     tmpvout = PETSC_TRUE;
    133:     tmpv    = &tmp;
    134:   }

    136:   /* Create vec on each proc, with the same size of the original mpi vec (all on process 0)*/
    137:   VecGetSize(vin,&N);
    138:   MPI_Comm_rank(PetscObjectComm((PetscObject)vin),&rank);
    139:   if (rank) N = 0;
    140:   VecCreateSeq(PETSC_COMM_SELF,N,tmpv);
    141:   /* Create the VecScatter ctx with the communication info */
    142:   ISCreateStride(PETSC_COMM_SELF,N,0,1,&is);
    143:   VecScatterCreate(vin,is,*tmpv,is,ctx);
    144:   ISDestroy(&is);
    145:   if (tmpvout) {VecDestroy(tmpv);}
    146:   return(0);
    147: }