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Summary of Commands

The following is a list of the commands available in XSPEC, together with a brief description of the purpose of each. The commands have been categorized under six headings: Control, Data, Fit, Model, Plot, Script, and Setting. The Control commands contain the interface with the operating system: they cause commands to be executed, or user input written to disk, or control how much is output. The Data commands manipulate the data being analyzed, by reading data into the program or replacing spectra or their ancillary detector, background, correction, or efficiency (auxiliary response) arrays. Additionally data commands control the channels under analysis. The fit commands invoke the fitting routines, modify their behavior by interchanging fitting algorithms or statistics in use, fixing parameters, or perform statistical testing. The Model commands create or manipulate the model, adding or editing components, modifying parameters, or alternatively performing analytical calculations from a model. The Plot commands deal with all aspects of plotting. The scripts are auto-loaded Tcl scripts that can be used in the same ways as commands. Finally the Setting commands sets variables that affect theoretical models.

 

Command

Category

Description

abund

Setting

Set the abundance table.

addcomp

Model

Add a component to the model.

addline

Model

Add lines to a model

arf

Data

Read an auxiliary response file.

autosave

Control

Periodically save the XSPEC status.

backgrnd

Data

Reset the files to be used for background subtraction.

bayes

Fit

Set up for Bayesian inference.

chain

Fit

Run a Monte Carlo Markov Chain.

chatter

Control

Control the verbosity of XSPEC.

corfile

Data

Reset the files to be used for background correction.

cornorm

Data

Reset the normalization to be used in correcting the background.

cosmo

Setting

Set H0, q0, and lambda_0

cpd

Plot

Alias for setplot device.

data

Data

Input one or more PHA data files.

delcomp

Model

Delete a component from the model.

diagrsp

Data

Diagonalize the current response for an ideal response.

dummyrsp

Model

Create a dummy response, covering a given energy range.

editmod

Model

Add, delete, or replace one component in the model.

energies

Model

Specify new energy binning for model fluxes.

eqwidth

Model

Calculate a model componentís equivalent width.

error (rerror)

Fit

Determine a single parameter confidence region. rerror is for response parameters.

exec

Control

Execute a shell command from within XSPEC.

exit

Control

Wind up any hardcopy plots and exit from XSPEC.

extend

Model

This is now obsolete.† See energies command.

fakeit

Data

Produce simulated data files for sensitivity studies.

fit

Fit

Find the best fit model parameters.

flux

Model

Calculate the current model's flux over an energy range.

freeze (rfreeze)

Fit

Do not allow a model parameter to vary during the fit. rfreeze is for response parameters.

ftest

Fit

Calculate the F-statistic between two model fits

gain

Model

Perform a simple modification of the response gain.

goodness

Fit

Monte Carlo calculation of goodness-of-fit.

hardcopy

Plot

Spool the current plot to the printer.

help

Control

Obtain help on XSPEC commands.

identify

Model

List possible lines in the specified energy range.

ignore

Data

Ignore a range of PHA channels in future fit operations.

initpackage

Model

Compile, build, and initialize a package of local models.

iplot

Plot

As plot command but interactive using PLT.

lmod

Model

Load a package of local models.

log

Control

Open the log file to save output.

lrt

Script

Likelihood ratio test between two models.

lumin

Model

Calculate the current model's luminosity over a given rest frame energy range and redshift.

margin

Fit

MCMC probability distribution.

mdefine

Model

Define a simple model using an arithmetic expression.

method

Setting

Set the minimization method.

model (rmodel)

Model

Define the model to be used when fitting the data.

modid

Model

Guess line IDs in the model.

multifake

Script

Perform many iterations of fakeit and save the results in a FITS file.

newpar (rnewpar)

Model

Modify the model parameters. rnewpar is for response parameters

notice

Data

Restore a range of PHA channels for future operations.

parallel

Control

Enable parallel processing for particular tasks in XSPEC.

plot

Plot

Plot various information on the current plot device.

query

Control

Switch on/off prompt to continue fitting.

quit

Control

An alias for exit

renorm

Fit

Adjust the model norms, and/or control automatic renorming.

rescalecov

Script

Rescale the covariance matrix used in the proposal chain command.

response

Data

Reset the files used to determine the detector responses.

save

Control

Save aspects of the current state to a command file.

script

Control

Open the script file to save all commands input.

setplot

Plot

Modify the plot device and other values used by the plot routines.

show

Control

Display current file and model information.

simftest

Script

Generate simulated datasets to estimate the F-test probability for adding a model component.

source

Control

Execute a script file.

statistic

Setting

Change the fit statistic in use.

steppar

Fit

Step through a range of parameter values; perform a fit at each step.

syscall

Control

Run a shell command.

systematic

Model

Set the model systematic error.

tclout

Control

write xspec data to a tcl variable

tcloutr

Control

tclout with return value

thaw (rthaw)

Fit

Allow a model parameter to vary during the fit. rthaw is for response parameters

time

Control

Display elapsed time and other statistical information.

uncertain

Fit

Alias for error

untie (runtie)

Model

Untie linked parameters. runtie is for response parameters.

version

Control

Print XSPEC version and build date/time

weight

Fit

Change the weighting function used for chi-squared fits.

writefits

Script

Write information about the current fit and errors to a FITS file.

xsect

Setting

Change the photoelectric absorption cross-sections in use.

xset

Setting

Modify a number of XSPEC internal switches

 

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Next: Description of Syntax Up: XSPEC Commands Previous: XSPEC Commands