Calculate the PI values for the input event file 'ixpe00000000_det1_evt1_v01.fits'.
The results are written in the output event file 'ixpe00000000_det1_evt1_v01_out.fits'.
> ixpegaincorrpkmap infile=ixpe00000000_det1_evt1_v01.fits outfile=ixpe00000000_det1_evt1_v01_out.fits
pkgainfile=ixpe00000000_det1_pkgainmap.fits