I have used test_gnfw.par to produce the files mass_nfw.fits and mass_gnfw.fits respectively by commenting and uncommenting the alpha keyword.

I have produced the catalogs of sources source.cat and image image.cat, with the NFW profile. runmode source 0 source.cat --> source 3 source.cat image 0 image.cat --> image 3 image.cat

Then I have recovered the slope, concentration and scale radius with the generalised NFW profile. runmode inverse 0 0.1 200 --> inverse 3 0.1 200