I installed a package called octave, which is a mathematical calculational software, but one of the commands for octave requires an outside program that is not installed as any type of dependency, so if you don't install the required package manually, the command in octave will not work. The version of octave is 2.1.72-1 which is in the extra repo. The octave command is called 'plot' without the quotes. The 'plot' command uses gnuplot to do the plotting, which is a completely separate package. When I tried to use 'plot' it gave me an error that said the following:

octave:4> plot
usage: plot (y)
plot (x, y, ...)
plot (x, y, fmt, ...)
error: evaluating if command near line 30, column 3
error: called from `__plt__' in file `/usr/share/octave/2.1.72/m/plot/__plt__.m'error: called from `plot' in file `/usr/share/octave/2.1.72/m/plot/plot.m'
octave:4> sh: gnuplot: command not found

warning: connection to external plotter (pid = 32097) lost --
warning: please try your plot command(s) again
warning: broken pipe -- some output may be lost
octave:4>


When I saw reference to the gnuplot package, I then manually installed the gnuplot package, version 4.0.0-1, which was in the extra repo, and the plot command for octave then worked. A simple fix for this problem would be to just add the gnuplot package as a dependency for octave.

Sincerely,

S. Chris Hellriegel