petsc-3.5.1 2014-07-24
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MatStoreValues

Stashes a copy of the matrix values; this allows, for example, reuse of the linear part of a Jacobian, while recomputing the nonlinear portion.

Synopsis

#include "petscmat.h" 
PetscErrorCode  MatStoreValues(Mat mat)
Collect on Mat

Input Parameters

mat -the matrix (currently only AIJ matrices support this option)

Common Usage, with SNESSolve()

   Create Jacobian matrix
   Set linear terms into matrix
   Apply boundary conditions to matrix, at this time matrix must have
     final nonzero structure (i.e. setting the nonlinear terms and applying
     boundary conditions again will not change the nonzero structure
   ierr = MatSetOption(mat,MAT_NEW_NONZERO_LOCATIONS,PETSC_FALSE);
   ierr = MatStoreValues(mat);
   Call SNESSetJacobian() with matrix
   In your Jacobian routine
     ierr = MatRetrieveValues(mat);
     Set nonlinear terms in matrix

Common Usage without SNESSolve(), i.e. when you handle nonlinear solve yourself

   // build linear portion of Jacobian
   ierr = MatSetOption(mat,MAT_NEW_NONZERO_LOCATIONS,PETSC_FALSE);
   ierr = MatStoreValues(mat);
   loop over nonlinear iterations
      ierr = MatRetrieveValues(mat);
      // call MatSetValues(mat,...) to set nonliner portion of Jacobian
      // call MatAssemblyBegin/End() on matrix
      Solve linear system with Jacobian
   endloop

Notes

Matrix must already be assemblied before calling this routine Must set the matrix option MatSetOption(mat,MAT_NEW_NONZERO_LOCATIONS,PETSC_FALSE); before calling this routine.

When this is called multiple times it overwrites the previous set of stored values and does not allocated additional space.

See Also

MatRetrieveValues()

Level:advanced
Location:
src/mat/impls/aij/seq/aij.c
Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages