[petsc-users] output vec

[Jed Brown]

likunt at caltech.edu writes:

> Dear Petsc developers,
>
> I am trying to output my vec M={m1 m2 m3 m4 m5 m6 ...} in a form like this:
>
> m1 m2 m3
> m4 m5 m6
> ...
>
> Here is my code to do this:
>
> ==================================================================
> PetscViewerASCIIOpen(PETSC_COMM_WORLD, NAME, &view);
> PetscViewerSetFormat(view, PETSC_VIEWER_ASCII_SYMMODU);
> PetscViewerASCIISynchronizedAllow(view, PETSC_TRUE);
> for(int step=0; step<STEP; step++)
> {
>     //calculate M at current step
>     DMDAVecGetArray(da, M, &aM);
>     DMDAGetCorners(da, &xs, 0, 0, &xm, 0, 0);
>     for(int node=xs; node<xs+xm; node++)
>     {
>        PetscViewerASCIISynchronizedPrintf(view, "%3.12f %3.12f %3.12f\n",
> aM[node].x, aM[node].y, aM[node].z);
>        PetscViewerFlush(view);
>     }
>     DMDAVecRestoreArray(da, M, &aM);
> }
> =================================================================
>
> but this turns out to be very slow. 

Yes, ASCII output is slow.

> I am trying to write it in a binary file, but I cannot find the
> corresponding functionality (such as PETSC_VIEWER_ASCII_SYMMODU and
> PetscViewerASCIISynchronizedPrintf in binary form).

Just use VecView to a binary viewer.
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