petsc-3.3-p7 2013-05-11

VecLoad

Loads a vector that has been stored in binary or HDF5 format with VecView().

Synopsis

#include "petscvec.h" 
PetscErrorCode  VecLoad(Vec newvec, PetscViewer viewer)

Collective on PetscViewer

Input Parameters

	newvec	- the newly loaded vector, this needs to have been created with VecCreate() or some related function before a call to VecLoad().
	viewer	- binary file viewer, obtained from PetscViewerBinaryOpen() or HDF5 file viewer, obtained from PetscViewerHDF5Open()

Notes

Defaults to the standard Seq or MPI Vec, if you want some other type of Vec call VecSetFromOptions() before calling this.

The input file must contain the full global vector, as written by the routine VecView().

If the type or size of newvec is not set before a call to VecLoad, PETSc sets the type and the local and global sizes.If type and/or sizes are already set, then the same are used.

IF using HDF5, you must assign the Vec the same name as was used in the Vec that was stored in the file using PetscObjectSetName(). Otherwise you will get the error message: "Cannot H5DOpen2() with Vec name NAMEOFOBJECT"

Notes for advanced users

Most users should not need to know the details of the binary storage format, since VecLoad() and VecView() completely hide these details. But for anyone who's interested, the standard binary matrix storage format is

     int    VEC_FILE_CLASSID
     int    number of rows
     PetscScalar *values of all entries

In addition, PETSc automatically does the byte swapping for machines that store the bytes reversed, e.g. DEC alpha, freebsd, linux, Windows and the paragon; thus if you write your own binary read/write routines you have to swap the bytes; see PetscBinaryRead() and PetscBinaryWrite() to see how this may be done.

Examples