VecView#

Views a vector object.

Synopsis#

#include "petscvec.h"   
PetscErrorCode VecView(Vec vec, PetscViewer viewer)

Collective

Input Parameters#

vec - the vector
viewer - an optional PetscViewer visualization context

Notes#

The available visualization contexts include

PETSC_VIEWER_STDOUT_SELF - for sequential vectors
PETSC_VIEWER_STDOUT_WORLD - for parallel vectors created on PETSC_COMM_WORLD
PETSC_VIEWER_STDOUT_(comm) - for parallel vectors created on MPI communicator comm

You can change the format the vector is printed using the option PetscViewerPushFormat().

The user can open alternative viewers with

PetscViewerASCIIOpen() - Outputs vector to a specified file
PetscViewerBinaryOpen() - Outputs vector in binary to a specified file; corresponding input uses VecLoad()
PetscViewerDrawOpen() - Outputs vector to an X window display
PetscViewerSocketOpen() - Outputs vector to Socket viewer
PetscViewerHDF5Open() - Outputs vector to HDF5 file viewer

The user can call PetscViewerPushFormat() to specify the output format of ASCII printed objects (when using PETSC_VIEWER_STDOUT_SELF, PETSC_VIEWER_STDOUT_WORLD and PetscViewerASCIIOpen()). Available formats include

PETSC_VIEWER_DEFAULT - default, prints vector contents
PETSC_VIEWER_ASCII_MATLAB - prints vector contents in MATLAB format
PETSC_VIEWER_ASCII_INDEX - prints vector contents, including indices of vector elements
PETSC_VIEWER_ASCII_COMMON - prints vector contents, using a format common among all vector types

You can pass any number of vector objects, or other PETSc objects to the same viewer.

In the debugger you can do call VecView(v,0) to display the vector. (The same holds for any PETSc object viewer).

Notes for binary viewer#

If you pass multiple vectors to a binary viewer you can read them back in in the same order with VecLoad().

If the blocksize of the vector is greater than one then you must provide a unique prefix to the vector with PetscObjectSetOptionsPrefix((PetscObject)vec,”uniqueprefix”); BEFORE calling VecView() on the vector to be stored and then set that same unique prefix on the vector that you pass to VecLoad(). The blocksize information is stored in an ASCII file with the same name as the binary file plus a “.info” appended to the filename. If you copy the binary file, make sure you copy the associated .info file with it.

See the manual page for VecLoad() on the exact format the binary viewer stores the values in the file.

Notes for HDF5 Viewer#

The name of the Vec (given with PetscObjectSetName() is the name that is used for the object in the HDF5 file. If you wish to store the same Vec into multiple datasets in the same file (typically with different values), you must change its name each time before calling the VecView(). To load the same vector, the name of the Vec object passed to VecLoad() must be the same.

If the block size of the vector is greater than 1 then it is used as the first dimension in the HDF5 array. If the function PetscViewerHDF5SetBaseDimension2()is called then even if the block size is one it will be used as the first dimension in the HDF5 array (that is the HDF5 array will always be two dimensional) See also PetscViewerHDF5SetTimestep() which adds an additional complication to reading and writing Vec with the HDF5 viewer.