MatView#

display information about a matrix in a variety ways

Synopsis#

#include "petscmat.h" 
PetscErrorCode MatView(Mat mat, PetscViewer viewer)

Collective on viewer

Input Parameters#

mat - the matrix
viewer - visualization context

Options Database Keys#

-mat_view ::ascii_info - Prints info on matrix at conclusion of MatAssemblyEnd()
-mat_view ::ascii_info_detail - Prints more detailed info
-mat_view - Prints matrix in ASCII format
-mat_view ::ascii_matlab - Prints matrix in MATLAB format
-mat_view draw - PetscDraws nonzero structure of matrix, using MatView() and PetscDrawOpenX().
-display - Sets display name (default is host)
-draw_pause - Sets number of seconds to pause after display
-mat_view socket - Sends matrix to socket, can be accessed from MATLAB (see Users-Manual: ch_matlab for details)
-viewer_socket_machine - -
-viewer_socket_port - -
-mat_view binary - save matrix to file in binary format
-viewer_binary_filename - -

Notes#

The available visualization contexts include

PETSC_VIEWER_STDOUT_SELF - for sequential matrices
PETSC_VIEWER_STDOUT_WORLD - for parallel matrices created on PETSC_COMM_WORLD
PETSC_VIEWER_STDOUT_(comm) - for matrices created on MPI communicator comm
PETSC_VIEWER_DRAW_WORLD - graphical display of nonzero structure

The user can open alternative visualization contexts with

PetscViewerASCIIOpen() - Outputs matrix to a specified file
PetscViewerBinaryOpen() - Outputs matrix in binary to a specified file; corresponding input uses MatLoad()
PetscViewerDrawOpen() - Outputs nonzero matrix structure to an X window display
PetscViewerSocketOpen() - Outputs matrix to Socket viewer. Currently only the MATSEQDENSE and MATAIJ matrix types support the Socket 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 matrix contents
PETSC_VIEWER_ASCII_MATLAB - prints matrix contents in MATLAB format
PETSC_VIEWER_ASCII_DENSE - prints entire matrix including zeros
PETSC_VIEWER_ASCII_COMMON - prints matrix contents, using a sparse format common among all matrix types
PETSC_VIEWER_ASCII_IMPL - prints matrix contents, using an implementation-specific format (which is in many cases the same as the default)
PETSC_VIEWER_ASCII_INFO - prints basic information about the matrix size and structure (not the matrix entries)
PETSC_VIEWER_ASCII_INFO_DETAIL - prints more detailed information about the matrix structure (still not vector or matrix entries)

The ASCII viewers are only recommended for small matrices on at most a moderate number of processes, the program will seemingly hang and take hours for larger matrices, for larger matrices one should use the binary format.

In the debugger you can do “call MatView(mat,0)” to display the matrix. (The same holds for any PETSc object viewer).

See the manual page for MatLoad() for the exact format of the binary file when the binary viewer is used.

See share/petsc/matlab/PetscBinaryRead.m for a MATLAB code that can read in the binary file when the binary viewer is used and lib/petsc/bin/PetscBinaryIO.py for loading them into Python.

One can use ‘-mat_view draw -draw_pause -1’ to pause the graphical display of matrix nonzero structure, and then use the following mouse functions.

  left mouse: zoom in
  middle mouse: zoom out
  right mouse: continue with the simulation

Level#

beginner

Location#

src/mat/interface/matrix.c

Examples#

src/mat/tutorials/ex4.c
src/mat/tutorials/ex12.c
src/mat/tutorials/ex17f.F90
src/mat/tutorials/ex18.c
src/mat/tutorials/ex11.c
src/tao/leastsquares/tutorials/cs1.c
src/mat/tutorials/ex8.c
src/mat/tutorials/ex16.c
src/mat/tutorials/ex4f.F90
src/mat/tutorials/ex17.c

Implementations#

Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages