[petsc-users] Large MATMPIAIJ - 32bit integer overflow in nz value

[Fleischli Benno HSLU T&A]

Dear PETSc developers

I am creating a very large parallel sparse matrix (MATMPIAIJ) with PETSc. I write this matrix to disk.
The number of non-zeros exceeds the maximum number a 32-bit integer can hold.
When I read the matrix from disk i get an error because there was an overflow in the nz number.
(see petsc-3.18.4/src/mat/impls/aij/seq/aij.c:4977)

Obviously I could compile PETSc with 64bit integers (--with-64-bit-indices).
But I wanted to ask if there is another way. Because the total number of nonzeros nz is the only numer that exceeds the 32bit limit.
It would not be efficient to use 64bit integers everywhere just because of this single number.

This how I configured PETSc:

./configure --download-fblaslapack --download-hpddm --download-hypre --with-debugging=0
COPTFLAGS='-O3 -march=native -mtune=native' CXXOPTFLAGS='-O3 -march=native -mtune=native'
FOPTFLAGS='-O3 -march=native -mtune=native' --with-scalar-type=real (--with-mpi-dir=/home/benno/Libraries/openMPI)



Kind Regards

Benno




________________________________

Hochschule Luzern
Technik & Architektur
Institute for Mechanical Engineering and Energy Technology

Competence Center Fluid Mechanics and Numerical Methods


Benno Fleischli
MSc in Mechanical Engineering / BSc in Electrical Engineering

Wissenschaftlicher Mitarbeiter

benno.fleischli at hslu.ch<https://webmail.hslu.ch/owa/redir.aspx?C=rM5K5xPd_kKJmyojcJXaG18BaXM9wM8IqSslYJQen5H6HtdiNS2KtWNFL89yfRdRtW-Oa6xCXTk.&URL=mailto%3akatrina.kemp%40hslu.ch>

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