Displaying More Than One Spectrum

 In Section  there are some plots with more than one spectra. The ability to plot two or more spectra on one set of axes is very useful sometimes.

When you send the new-plot command SPECX closes the old plot file and opens a new, clean one. The trick of getting more than one spectra is not to close the plot before you're done adding things to it. This is done using the overlay command, as we have already seen. There is a close-plot command by the way, which is useful particularly when you are working with output to a plotfile ultimately destined for printing.

You can keep on using overlay for any number of spectra. If you want a decent plot remember to offset them vertically one from another (use the offset command). Also, you can't change the plot scales after you've opened a plot so make it big enough before you start.