Bugs: atten

Bugs

1. 'atten' model parameter values are erroneously returned in energy units.

Bugs

1. 'atten' model parameter values are erroneously returned in energy units.

   Currently, the Sherpa atten (S-Lang or Python help) model erroneously returns model parameter values in energy units, as the internal grid of this model is defined in Angstroms; this will be fixed in a future release. This is the case even if the command set_analysis("wave") (S-Lang or Python help) has been issued.

   Workaround:

   The (Python) workaround involves defining a Sherpa user model which allows atten to be used in wavelength analysis. The user model "atten_wave" is defined in the following example, and is assigned an ID of "abs1". For more on Sherpa user models, see the thread "Sherpa User Models" (S-Lang or Python).

   sherpa> set_analysis("wave")
   sherpa> hc = 12.39841874  #in [keV-Angstrom]
   sherpa> dummy = atten.dummy
   sherpa> dummy.integrate = False
   sherpa> def atten_wave(p, *energ_args, **kwargs):
               wave_args = [hc/arg for arg in energ_args[::-1]]
               return dummy.calc(p, *wave_args, **kwargs)
   
   sherpa> load_user_model(atten_wave, "abs1")
   sherpa> add_user_pars("abs1", ['hcol','heiRatio','heiiRatio'],
                 [dummy.hcol.val,dummy.heiRatio.val,dummy.heiiRatio.val],
                 [dummy.hcol.min,dummy.heiRatio.min,dummy.heiiRatio.min],
                 [dummy.hcol.max,dummy.heiRatio.max,dummy.heiiRatio.max],
                 [dummy.hcol.units,dummy.heiRatio.units,dummy.heiiRatio.units],
                 [False,False,False])
   
   sherpa> set_model(abs1)
   sherpa> fit()