help on plot in octave

[Ben Abbott]

On Jun 19, 2009, at 9:28 PM, Jason Ding wrote:
>
> -----Original Message-----
> From: Ben Abbott [mailto:bpabbott at mac.com]
> Sent: Friday, June 19, 2009 5:42 PM
> To: Jason Ding
> Cc: help-octave at octave.org
> Subject: Re: help on plot in octave
>
>
> On Jun 19, 2009, at 8:11 PM, Jason Ding wrote:
>
>>
>> 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
>>
>>
>> Ben,
>>
>> Thanks for your reply. Here is  more info about OS, GNUplot and
>> octave.
>> Terminal type is set to x11, gnuplot is 4.0 and octave is 3.2.0.
>>
>> Thanks,
>> Jason
>>
>> OS:
>>
>> Linux version 2.6.18-92.el5 (mockbuild at builder10.centos.org) (gcc
>> version 4.1.2 20071124 (Red Hat 4.1.2-42)) #1 SMP Tue Jun 10 18:51:06
>> EDT 2008
>>
>> GNUPLOT:
>>
>>    Version 4.0 patchlevel 0
>>       last modified Thu Apr 15 14:44:22 CEST 2004
>>       System: Linux 2.6.18-92.el5
>>
>>       Copyright (C) 1986 - 1993, 1998, 2004
>>       Thomas Williams, Colin Kelley and many others
>>
>>       This is gnuplot version 4.0.  Please refer to the documentation
>>       for command syntax changes.  The old syntax will be accepted
>>       throughout the 4.0 series, but all save files use the new
>> syntax.
>>
>>       Type `help` to access the on-line reference manual.
>>       The gnuplot FAQ is available from
>>               http://www.gnuplot.info/faq/
>>
>>       Send comments and requests for help to
>>               <gnuplot-info at lists.sourceforge.net>
>>       Send bugs, suggestions and mods to
>>               <gnuplot-bugs at lists.sourceforge.net>
>>
>>
>> Terminal type set to 'x11'
>>
>>
>> Octave:
>>
>> GNU Octave, version 3.2.0
>> Copyright (C) 2009 John W. Eaton and others.
>> This is free software; see the source code for copying conditions.
>> There is ABSOLUTELY NO WARRANTY; not even for MERCHANTABILITY or
>> FITNESS FOR A PARTICULAR PURPOSE.  For details, type `warranty'.
>>
>> Octave was configured for "x86_64-unknown-linux-gnu".
>>
>> Additional information about Octave is available at
>> http://www.octave.org.
>>
>> Please contribute if you find this software useful.
>> For more information, visit http://www.octave.org/help-wanted.html
>>
>> Report bugs to <bug at octave.org> (but first, please read
>> http://www.octave.org/bugs.html to learn how to write a helpful
>> report).
>>
>> For information about changes from previous versions, type `news'.
>>
>> octave:1>
>>
>
> It appears that the problem may be that you are running a rather old
> version of gnuplot.
>
> Can you upgrade to a version more recent than 4.2.2 (the latest
> release if 4.2.5).
>
> Ben
>
>
> Ben,
> Thanks for the suggestion. I installed gnuplot4.2.5 and tested it ok.
> Then I changed the gnuplot_binary to this new gnuplot4.2.5 binary. Run
> octave3.0, I got the same errors as before but I did get a warning
> saying gnuplot_binary is not a built-in variable.
>
> Thanks,
> Jason
>
> The following screen captures for running new gnuplot and octave:
>
> [jding at chip5 bin]$ ./gnuplot
>
>        G N U P L O T
>        Version 4.2 patchlevel 5
>        last modified Mar 2009
>        System: Linux 2.6.18-92.el5
>
>        Copyright (C) 1986 - 1993, 1998, 2004, 2007 - 2009
>        Thomas Williams, Colin Kelley and many others
>
>        Type `help` to access the on-line reference manual.
>        The gnuplot FAQ is available from http://www.gnuplot.info/faq/
>
>        Send bug reports and suggestions to
> <http://sourceforge.net/projects/gnuplot>
>
>
> Terminal type set to 'x11'
>
> [jding at chip5 ~]$ octave
> GNU Octave, version 3.2.0
> Copyright (C) 2009 John W. Eaton and others.
> This is free software; see the source code for copying conditions.
> There is ABSOLUTELY NO WARRANTY; not even for MERCHANTABILITY or
> FITNESS FOR A PARTICULAR PURPOSE.  For details, type `warranty'.
>
> Octave was configured for "x86_64-unknown-linux-gnu".
>
> Additional information about Octave is available at
> http://www.octave.org.
>
> Please contribute if you find this software useful.
> For more information, visit http://www.octave.org/help-wanted.html
>
> Report bugs to <bug at octave.org> (but first, please read
> http://www.octave.org/bugs.html to learn how to write a helpful  
> report).
>
> For information about changes from previous versions, type `news'.
>
> warning: gnuplot_binary is no longer a built-in variable; please read
> the NEWS file or type `news' for details
> gnuplot_binary = /home/jding/usr/bin/gnuplot
> octave:1>

Jason, please reply at the bottom to allow new comers to follow along  
more naturally.

Notice the warning regarding the "gnuplot_variable".

Please type the following at Octave's prompt to confirm Octave sees  
gnuplot 4.2.5

	__gnuplot_version__

If you have 4.2.5 installed correctly, you will see ...

	ans = 4.2.5

Ben