Multi-panel figures

To assemble multiple Frida plots into a single PostScript file:

1. Plot the first panel and save it: gp
2. Plot each subsequent panel and append: gfa

The setpagegrid line in the header section controls automatic layout:

2 4 12.6 -12.6 setpagegrid    % 2 columns, 4 rows; horizontal/vertical offsets

For arbitrary placement, use <x> <y> offset instead of nextFrame.

Workflow example

0 > p          # plot first spectrum
0 > gp         # save as l001.ps
0 > pn         # plot next spectrum
0 > gfa        # append to l001.ps
0 > pn
0 > gfa        # append third panel

Open the file in Evince (or another auto-reloading PostScript viewer) to see the assembled figure update after each gfa.