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Last modified: December 2006

URL: http://cxc.harvard.edu/ciao3.4/run.html
Hardcopy (PDF): A4 | Letter
AHELP for CIAO 3.4 run Context: sherpa

Synopsis

Summary of Sherpa/S-Lang module run functions.

Description

Most commands issued in Sherpa cause it to do tasks that are accomplished quickly. However, several cause Sherpa to begin potentially time-consuming tasks, like FIT, PROJECTION, etc. This time consumption could make life difficult for the novice user if he or she was to do something like this:

sherpa> projection
[...done 20 minutes later...]
["Hmm, I'd like to save those results in S-Lang scope..."]
sherpa> p = do_projection()   # (does not actually exist)
[...done 20 minutes later...and the user is somewhat disturbed...]

To avoid this, the Sherpa/S-Lang module utilizes two different kinds of functions: run functions that actually perform time-consuming tasks and return the results, and get analogues to the run functions which simply return the most recent relevant results. Applied to the situation above, the second 20-minute run would be avoided: the results would be carried into S-Lang scope instantly. Or the user could have just typed run_projection in the beginning to achieve the same result.

Summary of Sherpa/S-Lang Module run Functions

Name Description
run_fit Fits datasets, and retrieves information about the fits
run_unc Determines confidence intervals, retrieves the parameter bounds
run_proj Determines confidence intervals, retrieves the parameter bounds
run_cov Determines confidence intervals, retrieves the parameter bounds
run_intunc Displays statistics as a function of parameter value, and retrieves the value and statistic arrays
run_intproj Displays statistics as a function of parameter value, and retrieves the value and statistic arrays
run_regunc Displays contours of statistics as a function of parameter values, and retrieves arrays of values and statistics
run_regproj Displays contours of statistics as a function of parameter values, and retrieves arrays of values and statistics

Bugs

Behavior when parameters fail to converge

If a fit is performed and some parameters fail to converge - e.g. when estimating errors using run_unc(), run_proj(), or run_cov() - then the routine will return a NULL even if there are valid results for some of the parameters. Currently the best way to check for this is to see if the corresponding get_unc(), get_proj(), or get_cov() call returns anything.

See the Sherpa bug pages online for an up-to-date listing of known bugs.

Hardcopy (PDF): A4 | Letter
Last modified: December 2006



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