Fix abs function

[jeanlucf22]

Issue reported by Jamal

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This change is 

[jeanlucf22]

@ares201005 It looks like the test now fails when using the proper 'abs' function. Shall we loosen the tolerance?

[jeanlucf22]

@ares201005 It looks like the test now fails when using the proper 'abs' function. Shall we loosen the tolerance?

@ares201005 Any comment?

[ares201005]

@ares201005 It looks like the test now fails when using the proper 'abs' function. Shall we loosen the tolerance?

@ares201005 Any comment?

Yes, I think we can loosen the tolerance. I am checking what's the proper tolerance.

[ares201005]

I found the issue comes from a but in prg_build_density_T_fermi_c where the drho value is passed to Fortran instead of reference so that the updated value in Fortran code is not passed back to C. Can I directly push my changes into your fabs branch? Otherwise I can make a separate PR as well.

[jeanlucf22]

I found the issue comes from a but in prg_build_density_T_fermi_c where the drho value is passed to Fortran instead of reference so that the updated value in Fortran code is not passed back to C. Can I directly push my changes into your fabs branch? Otherwise I can make a separate PR as well.

Thanks @ares201005 , looks good now