GFortran and OpenBLAS

I use GFortran on Fedora Linux 36, which uses OpenBLAS as the system BLAS/LAPACK library. When I add the -lblas -llapack flags to GFortran, does GFortran use OpenBLAS? If not, how can I use OpenBLAS with GFortran?

The OpenBLAS shared library would be named Use -lopenblas to link against it. Just the one flag is enough.

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A far as I know OpenBLAS already includes its own implementation of LAPACk, unlike the BLAS implementation from

But Iam not sure whether I remember correctly. Maybe there are also symbolic links involved.

In case of BLAS Level 2 and Level 3 routines, you can also try to experiment with the -fexternal-blas and -fblas-matmul-limit flags for gfortran. These options are discussed in the thread: Mapping matrix & vector arithmetic to BLAS calls

How do I make OpenBLAS use all threads?

You could try setting one of these env vars