XSPEC uses the PLT library, which is in turn based on PGPLOTD.1, to implement its plotting capabilities.
Extensive documentation for the PLT graphics routine is available in the The QDP/PLT Users's Guide and from PLT's interactive help. This appendix is intended to provide information to assist in using PLT from within the XSPEC program.
Within XSPEC, it is possible to set your graphics device using the cpd command. Any PGPLOT device supported by your local version of PGPLOT is accepted. The cpd command can also be used to display a list of all PGPLOT devices. If you fail to enter a device name, you will be prompted for a PGPLOT device every time you generate a new plot.
From XSPEC, there are two ways to call the PLT routine. Both have the same syntax which is described in the corresponding manual section.
The plot <plot mode> command will produce a graph and control will return immediately to XSPEC.
The iplot <plot mode> command will put XSPEC into interactive plot mode. The prompt
PLT>will appear after XSPEC has finished producing the graph. At this point, you can enter PLT commands to inspect interesting parts of the graph, add labels, or make a hardcopy file for later printing.
Getting started with PLT
In the following description of PLT commands, the full command is described. Capital letters denote the shortest abbreviation of the command that will be recognized. Here is a brief guide to some of the PLT commands that can be entered when iplot is invoked.
PLT Command summary
|CLear||Immediately clear the graphics device|
|COlor||Change the default colour index|
|CONtour||Produce a contour plot|
|CPD||Change the plotting device|
|CQuit||Clear the graphics device and return control to XSPEC|
|CSize||Change the default character size|
|Error||Control whether errors are displayed and used in fitting|
|EXit||Exit PLT and return control to XSPEC|
|Fit||Fit the PLT model to the data|
|FNy||Evaluate the model at the specified location|
|FOnt||Change the default text font|
|Freeze||Freeze a parameter value|
|GAp||Change the default gap size between the data and the edge|
|Grid||Control the location of the major and minor tic marks|
|Hardcopy||Make a file that can later be printed|
|HElp||Obtain help on any PLT command|
|Imodel||Numerically integrate the model over specified range|
|LAbel||Add or remove labels from the plot|
|LIne||Control whether a line is used to connect data points|
|LOg||Control whether data is plotted using a log10 scale|
|LStyle||Change the default style of the line connecting the data points|
|LWidth||Change the default line width|
|MArker||Control whether the data points are plotted with markers|
|MOdel||Define a PLT model|
|Newpar||Change a parameter value associated with the model|
|PLot||Immediately re-plot the data|
|PRompt||Change the PLT prompt|
|Rescale||Reset the minimum and maximum plot range|
|SCr||Change the color representation of the specified color index|
|SHow||Display the values of PLT internal variables|
|SKip||Control how PLT divides data into vectors|
|STatistics||Compute various statistical properties of the data|
|THaw||Allow a parameter value to vary during a fit|
|Time||Control whether the time stamp is plotted|
|Uncertainty||Compute the uncertainty in a parameter value|
|VErsion||Display date of the most recent modification to PLT|
|Viewport||Control the size of the viewport plotting area|
|WData||Write a QDP data file to disk|
|WEnviron||Write both QDP data and header files to disk|
|WHead||Write a QDP header file to disk|
|WModel||Write a model file to disk|
|Xaxis||Define the method used to calculate the x-variable|
|Yaxis||Define the y-axis scale for a contour plot|
|$||Execute operating system commands|
|@filename||Read commands from a PLT command (.pco) file|