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Last modified: December 2006

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

Synopsis

Configure COVARIANCE in Sherpa.

Syntax

sherpa.cov.[field]

Description

The Sherpa configuration variable (also called "state object") sherpa.cov contains settings of COVARIANCE for calculating confidence intervals in Sherpa. See ahelp COVARIANCE for more details.

The structure field is:

Field Description
sigma Specifies the number of sigma (i.e., the change in statistic).

To restore the default settings of sherpa.cov at any time, use the Sherpa/S-Lang module function restore_cov.

Example 1

sherpa> sherpa.cov.sigma = 2.6

This command sets confidence intervals calculated with COVARIANCE to 2.6 sigma.

Example 2

sherpa> sherpa.cov.sigma=1.6
sherpa> list_cov
Parameter Current Default Description
sigma 1.6 1 Number of sigma

The first command sets confidence intervals calculated with COVARIANCE to 1.6 sigma. The second command lists the current and default setting of sherpa.cov field to the screen as shown in the table.

Example 3

sherpa> variable sc = sherpa.cov
sherpa> sc.sigma = 2

The example shows how to create aliases for sherpa.cov in the first command and how to use the alias in the second command.

Bugs

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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