How Graphical Output is Produced

SPECTRA produces graphical output by calling internal drivers. Since no other program packages are involved, the graphical output is platform independent.

Lines, markers and texts are written to terminals or Postscript files using graphical attributes which are part of the GQEs that are displayed, e.g.:

$ xspectra
SPECTRA> read bpu1
SPECTRA> display

The SCAN bpu1 is read from a disk file. The graphical attributes are set to default values. The display command shows a rather primitive view of the data.

A more sophisticated output is generated by changing the default attributes. This can be done in a menu, with change (sect. 15.3.6) or by a set command (sect. 15.3.69).