Can somebody help me figure it out the solver options for the attached
generalized eigenvalue problem?
A x = lambda B x
where A and B have the same null space, with 5 zero eigenvalues.
The only non indefinite eigenvalue should be 41.1892
The problem is Hermite semi-positive so automatically slepc should purify it,
but to be sure I added
EPSSetPurify(eps, PETSC_TRUE);
I guess with my non-solver-options slepc is still trying to do the inverse of
the full
B matrix with an LU decomposition and gets zero pivot.
This is what I get as a PETSC error Message
[0]PETSC ERROR: --------------------- Error Message
--------------------------------------------------------------
[0]PETSC ERROR: Zero pivot in LU factorization:
https://www.mcs.anl.gov/petsc/documentation/faq.html#zeropivot
[0]PETSC ERROR: Bad LU factorization
[0]PETSC ERROR: See https://www.mcs.anl.gov/petsc/documentation/faq.html for
trouble shooting.
[0]PETSC ERROR: Petsc Development GIT revision: v3.11.3-2263-gce77f2ed1a
GIT Date: 2019-09-26 13:31:14 -0500
[0]PETSC ERROR: Nitsche_ex4a on a arch-linux2-c-opt named linux-8biu by
eaulisa Tue Jul 7 10:17:55 2020
[0]PETSC ERROR: Configure options --with-debugging=0 --with-x=1
COPTFLAGS="-O3 -march=native -mtune=native" CXXOPTFLAGS="-O3 -march=native
-mtune=native" FOPTFLAGS="-O3 -march=native -mtune=native" --download-openmpi=1
--download-fblaslapack=1 --download-hdf5=1 --download-metis=1
--download-parmetis=1 --with-shared-libraries=1 --download-blacs=1
--download-scalapack=1 --download-mumps=1 --download-suitesparse
[0]PETSC ERROR: #1 MatLUFactor_SeqDense() line 633 in
/home/eaulisa/software/petsc/src/mat/impls/dense/seq/dense.c
[0]PETSC ERROR: #2 MatLUFactorNumeric_SeqDense() line 432 in
/home/eaulisa/software/petsc/src/mat/impls/dense/seq/dense.c
[0]PETSC ERROR: #3 MatLUFactorNumeric() line 3056 in
/home/eaulisa/software/petsc/src/mat/interface/matrix.c
[0]PETSC ERROR: #4 PCSetUp_LU() line 126 in
/home/eaulisa/software/petsc/src/ksp/pc/impls/factor/lu/lu.c
[0]PETSC ERROR: #5 PCSetUp() line 894 in
/home/eaulisa/software/petsc/src/ksp/pc/interface/precon.c
[0]PETSC ERROR: #6 KSPSetUp() line 377 in
/home/eaulisa/software/petsc/src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: #7 STSetUp_Shift() line 119 in
/home/eaulisa/software/slepc/src/sys/classes/st/impls/shift/shift.c
[0]PETSC ERROR: #8 STSetUp() line 271 in
/home/eaulisa/software/slepc/src/sys/classes/st/interface/stsolve.c
[0]PETSC ERROR: #9 EPSSetUp() line 273 in
/home/eaulisa/software/slepc/src/eps/interface/epssetup.c
[0]PETSC ERROR: #10 EPSSolve() line 136 in
/home/eaulisa/software/slepc/src/eps/interface/epssolve.c
Thanks
Eugenio
Eugenio Aulisa
Department of Mathematics and Statistics,
Texas Tech University
Lubbock TX, 79409-1042
room: 226
http://www.math.ttu.edu/~eaulisa/
phone: (806) 834-6684
fax: (806) 742-1112
#include "slepceps.h"
int main(int argc, char** args) {
SlepcInitialize(&argc, &args, PETSC_NULL, PETSC_NULL);
double a[6][6] = {{0.0, 0.0, 0.0, 0.0, 0.0, 0.0},
{0.0, 1.9247225877689356, -1.9247225877689356, -0.96236129388446778, 0.0, 0.96236129388446778 },
{0.0, -1.9247225877689356, 1.9247225877689356, 0.96236129388446778, 0.0, -0.96236129388446778},
{0.0, -0.96236129388446778, 0.96236129388446778, 0.48118064694223389, 0.0, -0.48118064694223389},
{0.0, 0.0, 0.0, 0.0, 0.0, 0.0},
{0.0, 0.96236129388446778, -0.96236129388446778, -0.48118064694223389, 0.0, 0.48118064694223389}
};
double b[6][6] = {{0.0, 0.0, 0.0, 0.0, 0.0, 0.0},
{0.0, 0.046728852764308028, -0.046728852764308028, -0.023364426382154014, 0.0, 0.023364426382154014},
{0.0, -0.046728852764308028, 0.046728852764308028, 0.023364426382154014, 0.0, -0.023364426382154014 },
{0.0, -0.023364426382154014, 0.023364426382154014, 0.011682213191077007, 0.0, -0.011682213191077007 },
{0.0, 0.0, 0.0, 0.0, 0.0, 0.0},
{0.0, 0.023364426382154014, -0.023364426382154014, -0.011682213191077007, 0.0, 0.011682213191077007 }
};
Mat A, B;
EPS eps;
MatCreateSeqDense(PETSC_COMM_SELF, 6, 6, NULL, &A);
MatCreateSeqDense(PETSC_COMM_SELF, 6, 6, NULL, &B);
for(int i = 0; i < 6 ; i++) {
for(int j = 0; j < 6; j++) {
MatSetValues(A, 1, &i, 1, &j, &a[i][j], INSERT_VALUES);
MatSetValues(B, 1, &i, 1, &j, &b[i][j], INSERT_VALUES);
}
}
MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY);
MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY);
MatAssemblyBegin(B, MAT_FINAL_ASSEMBLY);
MatAssemblyEnd(B, MAT_FINAL_ASSEMBLY);
EPSCreate(PETSC_COMM_SELF, &eps);
EPSSetOperators(eps, A, B);
EPSSetWhichEigenpairs(eps, EPS_LARGEST_MAGNITUDE);
EPSSetPurify(eps, PETSC_TRUE);
EPSSetFromOptions(eps);
EPSSolve(eps);
EPSDestroy(&eps);
MatDestroy(&A);
MatDestroy(&B);
return 1;
}
