Re: fakeit command for multiple RMF/ARFs

On Fri, Apr 18, 2003 at 15:09 -0400, Marc Audard wrote:
> Hi-
> 
> I would like to fit HEG+1 and HEG-1 data althogether, and based on the
> best-fit, create Monte Carlo simulations using the RMF/ARF for HEG-1
> and RMF/ARF HEG+1. Then I'd like to fit the faked data together.
> 
> I have assigned the RMF/ARFs to non-exisiting histograms:
> 
> ignore([1:2]);
> assign_arf(1,5);   % assigning to non-existent histogram index creates one.
> assign_arf(2,6);   % assigning to non-existent histogram index creates one.
> assign_rmf(1,[5:6]);
> xnotice([5:6], xlo, xhi);
> 
> however, how can I issue a fakeit command so that it knows it has to fake
> 1 spectrum per histogram with the appropriate RMF/ARF combination?
> Or does the fakeit command do it by itself?


Hi Marc,

fakeit() will automatically operate on all the fake datasets
using the responses assigned to each.  Any "real" datasets
loaded at the time should be unaffected.

For example, you could load a set of XMM responses and a set of
Chandra responses and then simultaneously generate both
simulations with one 'fakeit'.


[...]
> 
> PS: additional question: rplot_counts does work only for 1 histogram index,
> correct? How can I plot the data, best-fit curve and residuals for 2 data
> sets in the same panel?


The best way would be to generate the plot using lower level
plot functions.  Perhaps something like


errorbars(1);

multiplot ([3,1]);

plot_data_counts(1);      % 4 curves in pane 1
oplot_model_counts(1);
oplot_data_counts(2);
oplot_model_counts(2);

_rplot_counts(1);     % plot residuals in pane 2
_orplot_counts(2);    % over-plot residuals in pane 2


One important caveat here: that last function, '_orplot_counts'
was added only very recently and I have not yet made it
available in the released isis.  

If you want to install a newer version of isis which has it,
let me know and I can provide a pre-release version sometime
later today (I'm fairly confident that its stable because it is
in constant use here).

Alternatively, if you don't want to mess with another install,
you could compute and plot fit residuals yourself with
something like:

  variable d, m;
  d = get_data_counts(1);
  m = get_model_counts(1);
  ohplot (d.bin_lo, d.bin_hi, d.value - m.value);

Thanks,

John  

-- 
John C. Houck                       MIT Center for Space Research
NE80-6005: 617-253-3849                   77 Massachusetts Avenue
42:21:55.105N, 71:05:28.122W             Cambridge, MA 02139-4307
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