Hello,
I am trying to use PetscOptionsGetString to retrieve the value of
an option in the options database, but the value returned in the last
argument indicates the option was not found. In the attached code (a
modified version of ksp example 2), the string "-ksp_pc_side" is passed
in as the argument name. If I run the code as
./jc2 -pc_type ilu -ksp_pc_side right
I get the output:
option -ksp_pc_side was found
from line 71 of the file. Petsc does not complain of unused
options when the program finishes. Am I using this function incorrectly?
Jared Crean
/*
static char help[] = "Solves a linear system in parallel with KSP.\n\
Input parameters include:\n\
-random_exact_sol : use a random exact solution vector\n\
-view_exact_sol : write exact solution vector to stdout\n\
-m <mesh_x> : number of mesh points in x-direction\n\
-n <mesh_n> : number of mesh points in y-direction\n\n";
*/
/*
Input parameters include:\n\
-random_exact_sol : use a random exact solution vector\n\
-view_exact_sol : write exact solution vector to stdout\n\
-m <mesh_x> : number of mesh points in x-direction\n\
-n <mesh_n> : number of mesh points in y-direction\n\n";
*/
/*T
Concepts: KSP^basic parallel example;
Concepts: KSP^Laplacian, 2d
Concepts: Laplacian, 2d
Processors: n
T*/
/*
Include "petscksp.h" so that we can use KSP solvers. Note that this file
automatically includes:
petscsys.h - base PETSc routines petscvec.h - vectors
petscmat.h - matrices
petscis.h - index sets petscksp.h - Krylov subspace methods
petscviewer.h - viewers petscpc.h - preconditioners
*/
#include <petscksp.h>
#include <iostream>
#undef __FUNCT__
#define __FUNCT__ "main"
int main(int argc,char **args)
{
Vec x,b; /* approx solution, RHS, exact solution */
Mat A; /* linear system matrix */
KSP ksp; /* linear solver context */
// PetscRandom rctx; /* random number generator context */
// PetscReal norm; /* norm of solution error */
PetscInt i,j,m = 3,n = 3,its;
PetscErrorCode ierr;
// PetscBool flg = PETSC_FALSE;
PetscScalar v;
//#if defined(PETSC_USE_LOG)
// PetscLogStage stage;
//#endif
PetscInitialize(&argc,&args,(char*)0,NULL);
// print value of an option
const char* pre = NULL;
const char name[] = "-ksp_pc_side";
const size_t len = 256;
char str[len];
PetscBool isset;
ierr = PetscOptionsGetString(pre, name, str, len, &isset);
CHKERRQ(ierr);
if (isset)
{
std::cout << "option " << name << " was found" << std::endl;
std::cout << "returned string is: " << str << std::endl;
} else
{
std::cout << "option " << name << " not found" << std::endl;
}
ierr = MatCreate(PETSC_COMM_WORLD,&A);CHKERRQ(ierr);
ierr = MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m,n);CHKERRQ(ierr);
ierr = MatSetFromOptions(A);CHKERRQ(ierr);
ierr = MatMPIAIJSetPreallocation(A,5,NULL,5,NULL);CHKERRQ(ierr);
ierr = MatSeqAIJSetPreallocation(A,5,NULL);CHKERRQ(ierr);
// ierr = MatGetOwnershipRange(A,&Istart,&Iend);CHKERRQ(ierr);
// ierr = PetscLogStageRegister("Assembly", &stage);CHKERRQ(ierr);
// ierr = PetscLogStagePush(stage);CHKERRQ(ierr);
for (i=0; i<m; i++) {
for (j=0; j<n; j++) {
v = i*n + j + 1;
std::cout << "inserting value " << v << " into position " << i << ", " << j << std::endl;
MatSetValues(A, 1, &i, 1, &j, &v, INSERT_VALUES); CHKERRQ(ierr);
}
}
// change one entry so it is non singular
i = 2;
j = 0;
v = 8;
std::cout << "inserting value " << v << " into position " << i << ", " << j << std::endl;
MatSetValues(A, 1, &i, 1, &j, &v, INSERT_VALUES); CHKERRQ(ierr);
// assemble matrix
ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
// ierr = PetscLogStagePop();CHKERRQ(ierr);
MatView(A,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
/*
Create parallel vectors.
- We form 1 vector from scratch and then duplicate as needed.
- When using VecCreate(), VecSetSizes and VecSetFromOptions()
in this example, we specify only the
vector's global dimension; the parallel partitioning is determined
at runtime.
- When solving a linear system, the vectors and matrices MUST
be partitioned accordingly. PETSc automatically generates
appropriately partitioned matrices and vectors when MatCreate()
and VecCreate() are used with the same communicator.
- The user can alternatively specify the local vector and matrix
dimensions when more sophisticated partitioning is needed
(replacing the PETSC_DECIDE argument in the VecSetSizes() statement
below).
*/
ierr = VecCreate(PETSC_COMM_WORLD,&b);CHKERRQ(ierr);
ierr = VecSetSizes(b,PETSC_DECIDE,m);CHKERRQ(ierr);
ierr = VecSetFromOptions(b);CHKERRQ(ierr);
// ierr = VecDuplicate(u,&b);CHKERRQ(ierr);
ierr = VecDuplicate(b,&x);CHKERRQ(ierr);
// set rhs
for (i=0; i < m; ++i)
{
v = i; //convert to scalar
ierr = VecSetValues(b, 1, &i, &v, INSERT_VALUES);CHKERRQ(ierr);
}
ierr = VecAssemblyBegin(b); CHKERRQ(ierr);
ierr = VecAssemblyEnd(b); CHKERRQ(ierr);
ierr = VecView(b, PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr);
/*
Create linear solver context
*/
ierr = KSPCreate(PETSC_COMM_WORLD,&ksp);CHKERRQ(ierr);
ierr = KSPSetOperators(ksp,A,A);CHKERRQ(ierr);
ierr = KSPSetTolerances(ksp,1.e-12,1.e-50,PETSC_DEFAULT,
PETSC_DEFAULT);CHKERRQ(ierr);
ierr = KSPSetFromOptions(ksp);CHKERRQ(ierr);
// solve
ierr = KSPSolve(ksp,b,x);CHKERRQ(ierr);
ierr = KSPGetIterationNumber(ksp,&its);CHKERRQ(ierr);
ierr = VecView(x,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
ierr = PetscPrintf(PETSC_COMM_WORLD, "Number of iterations = %d\n", its);CHKERRQ(ierr);
Mat B, C;
ierr = MatConvert(A, MATSAME, MAT_INITIAL_MATRIX, &B); CHKERRQ(ierr);
std::cout << "pointer C = " << C << std::endl;
ierr = PetscPrintf(PETSC_COMM_WORLD, "Mat B = \n"); CHKERRQ(ierr);
ierr = MatView(B, PETSC_VIEWER_STDOUT_SELF); CHKERRQ(ierr);
// multiply matrices
std::cout << "sizeof(MAT_INITIAL_MATRIX) = " << sizeof(MAT_INITIAL_MATRIX) << std::endl;
ierr = MatMatMult(A, B, MAT_INITIAL_MATRIX, PETSC_DEFAULT, &C); CHKERRQ(ierr);
// view result
ierr = PetscPrintf(PETSC_COMM_WORLD, "Mat C = \n"); CHKERRQ(ierr);
ierr = MatView(C, PETSC_VIEWER_STDOUT_WORLD); CHKERRQ(ierr);
// cleanup
ierr = KSPDestroy(&ksp);CHKERRQ(ierr);
ierr = VecDestroy(&x);CHKERRQ(ierr);
ierr = VecDestroy(&b);CHKERRQ(ierr); ierr = MatDestroy(&A);CHKERRQ(ierr);
ierr = PetscFinalize();
return 0;
}
