Chandra X-Ray Observatory
	(CXC)
Skip to the navigation links
Last modified: December 2013

URL: http://cxc.harvard.edu/sherpa/ahelp/set_par.html
Jump to: Description · Examples · Bugs · See Also


AHELP for CIAO 4.9 Sherpa v1

set_par

Context: modeling

Synopsis

Set initial values for a model parameter

Syntax

set_par( par, val=None, min=None, max=None, frozen=None )

Description

The set_par command sets the parameter fields which include starting value, the allowed limits, and whether or not the parameter should be frozen during a fit.

  • par - model parameter name and component, e.g. "bb1.kT"
  • val - initial parameter value; default=None
  • min - minimum limit; default=None
  • max - maximum limit; default=None
  • frozen - should the parameter be allowed to vary during the fit; default=None

Example 1

sherpa> set_par(g.pos, val=15.5)

The mean position parameter of a gauss1d model "g" is set to value 15.5.

Example 2

sherpa> set_par (clus.xpos, val=175, min=20, max=380)
sherpa> set_par (clus.ypos, val=180, min=20, max=320)

The value and limits are set for a beta2d model named "clus".

Example 3

sherpa> set_par(g.ampl, frozen=True)

Freeze the amplitude parameter of a gauss1d model "g".

Bugs

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

See Also

confidence
set_conf_opt, set_covar_opt, set_proj_opt
contrib
renorm
data
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
filtering
set_filter
methods
set_iter_method, set_iter_method_opt, set_method, set_method_opt
modeling
freeze, get_par, guess, link, paramprompt, set_bkg_model, set_full_model, set_pileup_model, set_source, set_xsabund, set_xscosmo, set_xsxsect, set_xsxset, thaw, unlink
statistics
set_prior, set_sampler, set_sampler_opt, set_stat
utilities
set_analysis, set_default_id
visualization
image_setregion

Last modified: December 2013
Smithsonian Institute Smithsonian Institute

The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email:   cxchelp@head.cfa.harvard.edu Smithsonian Institution, Copyright © 1998-2017. All rights reserved.