help on plot in octave

[Ben Abbott]

On Jun 19, 2009, at 6:31 PM, Jason Ding wrote:

> Hi, All,
>
> I installed both gnuplot and Octave. Gnuplot and octave work well  
> separately.  When I tried to use the “plot” function in octave, I  
> got the following errors after seeing an empty figure window popping  
> up. Can anyone have the similar experience? Or what may cause this?
>
> Thanks, a lot.
>
>
> if (exists("GPVAL_TERM")) print GPVAL_TERM; else print NaN
>                     ^
>          line 0: invalid expression
>
> error: Invalid call to strcat.  Correct usage is:
>
>  -- Function File:  strcat (S1, S2, ...)


Please include the OS your are using as well as the version of Octave  
and gnuplot.

The first error, complaining of GPVAL_TERM, appears to be from  
gnuplot. The "strcat" error is from Octave (but is only occurring  
because of the 1st error).

Assuming your Octave version is > 3.0 and your gnuplot is 4.2.2 or  
more recent, it is likely that you don't have a default terminal type  
set for gnuplot.

You'll want to set the GNUTERM environment variable. For Linux it  
should be set to "x11" or "wxt". For Mac OSX it can be set to "x11" or  
"aqua". For Windows  (I think) it can be set to "windows" and if you  
have x11 installed, then "x11" should also work (I'm guessing as I  
haven't used windows in years).

Ben