How to switch PETSc to 64 bit?

Hello,

I need to switch PETSc to 64 bit indices. I need to run ./configure --with-64-bit-indices, but where do I run it? Do i just input it into the command prompt before I run the file or does it go in the .edp?

Thank you for your help.

Hello,
Are you sure you need that? Are you solving problems with more than 4,294,967,296 unknowns? On how many MPI processes?
You can edit 3rdparty/ff-petsc/Makefile and add --with-64-bit-indices=true in the configure line.

Im solving a eigenvector problem of the Laplacian on a triangle. I want to do the first 1250 eigenvalues and have 450 nodes on each side. When I try to run the file that is the error it says. Does this sound like I should have to use 64 bit?

No, clearly you shouldn’t need 64 bit integers for such a problem. Could you please share a MWE?