METIS_OPTION_NUMBERING is essentially undocumented about metis

[Fabian188]

I'm quite lost with the defaults. I thought it works like

        idx_t options[METIS_NOPTIONS];
        METIS_SetDefaultOptions(options);

But all values I check, including options[METIS_OPTION_NUMBERING], are set to -1?!

[thk686]

Indeed:

int METIS_SetDefaultOptions(idx_t *options) 
{
  iset(METIS_NOPTIONS, -1, options);
  return METIS_OK;
}

[thk686]

Looks like its zero:

ctrl->numflag   = GETOPTION(options, METIS_OPTION_NUMBERING, 0);

[thk686]

So It appears that -1 in the options indicates to use the default rather than being the default. The confusing part is that all the options are copied into the ctrl structure.

[Fabian188]

That makes indeed sense if the defaults are selected depending on the actual data (now or in the future).

[Fabian188]

Thanks for the clarifications via code quotes.