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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.

  • HElp will provide you with descriptions of the PLT commands.
  • Plot redraws the display using all of the commands that change the graph entered since the last plot.
  • Rescale followed by two numbers, will set the minimum and maximum of the plotted x-range to the numbers specified. Without further arguments, Rescale X or Rescale Y will reset the minimum and maximum values to their default values. Rescale also updates the screen immediately. Other commands allow you to make several changes to the the graph without having to wait for the screen to be updated after every change.
  • LAbel <Top,X,Y> [<string>] adds labels to various locations on the graph. For example, typing LA Top EXOSAT was great will cause the message “EXOSAT was great” to appear at the top of the graph the next time the display is redrawn. Without the string argument the current label for Top, X, or Y is set to the empty string.
  • Hardcopy [?, PGPLOT plot device] creates a file that can later be printed. Since it redraws the graph and sends it to a file, it does not reproduce what currently is visible on the graphics display, but rather what you would see if you re-issued the Plot command. With the optional “?” argument, Hardcopy returns the current hardcopy plotting device. This can be overridden with Hardcopy [PGPLOT device name].
  • WData writes a QDP data file to disk. The wdata output file depends on how complicated the plot is (ie. multiple spectra, models, etc.); for the standard case of "plot data" with 1 spectrum and a fitted model, 5 columns of data are given:
    • col 1: x-axis value (same for both spectrum and model, in either channel energy or wavelength units depending on the plot)
    • col 2: x-axis error. Half of the bin-width, in either channel, energy, or wavelength units
    • col 3: y-axis value for the spectral data point
    • col 4: y-axis error for spectral data point (the +/- length of the error bars)
    • col 5: y-axis value for the model
    Since the models aren't plotted with y-axis errors, there is no col 6 for the model error. If plotting of additive components had been turned on then there would be one additional column for each additive component. If there are multiple spectra plotted then they are separated in the output file by a line of NOs with one NO for each column.
  • EXit returns control to XSPEC. Any changes you have made to the plot will be lost.

next up previous contents
Next: Example QDP file Up: Overview of PLT Previous: Overview of PLT   Contents