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Last modified: December 2013

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AHELP for CIAO 4.9 Sherpa v1


Context: confidence


Set the options for confidence


set_conf_opt( name, val )


The set_conf_opt command allows the user to set the options for the confidence parameter estimation method (see "ahelp conf").

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

A list of the available options is returned by the get_conf_opt command (see "ahelp get_conf"), e.g.:

sherpa> print(get_conf_opt())
{'verbose': False, 'openinterval': False, 'max_rstat': 3, 'maxiters':
200, 'soft_limits':False, 'eps': 0.01, 'fast': False, 'maxfits': 5,
'remin': 0.01, 'tol': 0.20000000000000001, 'sigma': 1, 'numcores': 2, 'parallel': True}
  • 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 optimization 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
  • openinterval - how the confidence function should behave when it cannot locate the root within the open interval; see "ahelp conf" for a detailed explanation; default=False
  • parallel - switch which allows confidence to be run as a parallel process; default=True
  • numcores - number of cores to use when conf command is run in parallel
  • 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
  • verbose - print information to the screen?; default=False

Example 1

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

Set the value of the "maxiters" confidence option to 400 and the "sigma" value to 3 for the next run of the confidence command.

Example 2

sherpa> set_conf_opt('numcores', 4)
sherpa> conf(2, g.gamma)

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


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_covar_opt, set_proj_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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