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Last modified: December 2013

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AHELP for CIAO 4.10 Sherpa v1


Context: confidence


Set the options for projection


set_proj_opt( name, val )


The set_proj_opt command sets the options for the projection parameter estimation method (see "ahelp proj"). Users are encouraged to use the confidence command (see "ahelp conf") in place of projection for estimating confidence intervals for thawed fit parameters.

  • name - projection option name
  • val - value for the option

A list of the available options is returned by the get_proj_opt command ("ahelp get_proj_opt"), e.g

{'eps': 0.01,
 'fast': False,
 'max_rstat': 3,
 'maxfits': 5,
 'maxiters': 200,
 'numcores': 2,
 'remin': 0.01,
 'sigma': 1,
 'soft_limits': False,
 'tol': 0.20000000000000001}
  • eps - precision of resulting limits, default=0.01
  • fast - if 'True', the fit optimization method is switched to a faster option to reduce the time per fit; default=False, so that the current method is used
  • max_rstat - maximum possible value of the reduced statistic, default=3
  • maxfits - maximum number of tries to fit the parameter space, default=5
  • maxiters- maximum number of tries to bracket desired limits, before returning, default=200
  • remin - if during search, a new fit statistic is found that is smaller than original best fit, the difference between new and original statistics must be greater than this value, default=0.01
  • sigma - to get 1, 2, or 3-sigma limits, default=1
  • soft_limits - a switch which allows the search to go all the way out to the hard parameter limits; if switched on, the search will be restricted to occur within the soft limits, which can be changed by the user, default=False
  • tol - tolerance for the fit, default=0.20000000000000001
  • parallel - Boolean to indicate if proj should be parallelized
  • numcores - number of cores to use in parallelization; default is to use all available cores


Example 1

sherpa> set_proj_opt ("maxiters", 400)
sherpa> set_proj_opt ("sigma", 3)

Set the "maxiters" value to 400 and the "sigma" value to 3 for the next run of projection.

Example 2

sherpa> set_proj_opt('numcores', 4)
sherpa> proj(2, g.gamma)

Use the set_proj_opt command to specify that all four of the available cores on the system should be utilized when the proj command is run. Compute parameter limits for the model parameter g.gamma, which is assigned to dataset 2. The output is:

projection 1-sigma bounds:
   Param            Best-Fit  Lower Bound  Upper Bound
   -----            --------  -----------  -----------
   g.gamma          2.15147   -0.0800326    0.0800326


See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

conf, covariance, get_conf, get_covar, get_int_proj, get_int_unc, get_proj, get_reg_proj, get_reg_unc, int_proj, int_unc, projection, reg_proj, reg_unc, set_conf_opt, set_covar_opt
set_areascal, set_arf, set_backscal, set_bkg, set_coord, set_counts, set_data, set_exposure, set_grouping, set_quality, set_rmf, set_staterror, set_syserror
set_iter_method, set_iter_method_opt, set_method, set_method_opt
get_par, set_bkg_model, set_full_model, set_par, set_pileup_model, set_source, set_xsabund, set_xscosmo, set_xsxsect, set_xsxset
set_prior, set_sampler, set_sampler_opt, set_stat
set_analysis, set_default_id

Last modified: December 2013
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