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Last modified: December 2010

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AHELP for CIAO 4.3 Sherpa v1


Context: info


Display the covariance information


show_covar([outfile=None, clobber=False] )


The show_covar command displays the results of the covariance command ("ahelp covariance") .

  • outfile - name of the file in which to store the information
  • clobber - a Boolean switch which indicates whether or not the 'outfile' should be overwritten, if the file already exists; default=False

The command output looks like:

Covariance:Dataset               = 1
Confidence Method     = covariance
Fitting Method        = neldermead
Statistic             = cstat
covariance 1-sigma (68.2689%) bounds:
   Param            Best-Fit  Lower Bound  Upper Bound
   -----            --------  -----------  -----------
   abs1.nh         0.0349312   -0.0108587    0.0108587
   p1.gamma          1.72895   -0.0636437    0.0636437
   p1.ampl       4.24936e-05 -2.19037e-06  2.19037e-06

The behavior of the screen output is determined by the user's $PAGER environment variable setting, which is usually a variant of "more." To disable paging within show_all() - i.e. print the entire contents, even if it scrolls offscreen - change this setting to "cat" before starting Sherpa:

unix% setenv PAGER cat

unix% sherpa

Example 1

sherpa> show_covar()

Print the covariance information for all datasets to the screen.

Example 2

sherpa> show_covar("sherpa.covar", True)

Write the covariance information to the file "sherpa.covar", clobbering any existing file with the same name.


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

See Also

list_bkg_ids, list_functions, show_all, show_bkg_model, show_bkg_source, show_conf, show_data, show_fit, show_method, show_model, show_proj, show_source, show_stat

Last modified: December 2010
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