Linking PGPLOT to octave

Using matwrap, the entire pgplot plotting library can be called from octave. (Actually, it uses the cpgplot interface.) Each function which you can call from C is available to be called from octave. Since I just took the cpgplot.h file and ran it through the wrapper generator, the interface is as low level as the C subroutines themselves (e.g., it doesn't autoscale, etc.). Perhaps someone wouldn't mind writing and distributing some higher level plotting functions make it easier to use?

To install and test it, perform the following steps:

Make sure your octave program supports dynamic loading of compiled functions. Some binary distributions do not. If you have the mkoctfile script, then you're probably ok.

Also, the pgplot wrapper code won't work with versions of octave before 2.0.0. Upgrade your octave if you have such an old version.
Install the pgplot libraries (libpgplot and libcpgplot somewhere on your system. These libraries must either be shared libraries (usually with an extension of .so) or else compiled in a format suitable for linking into a shared library. On some systems, this means you must use the -fPIC option to gcc, for example. Some systems, such as Digital Unix, do not require any special options for compilation. Check your system's documentation for producing shared libraries.
Fetch the pgplot wrapper code. The pgplot wrapper is included with the matwrap distribution. If you just want the code and don't want the wrapper generator itself, then you need several things:
- pgplot_octave.cc for pgplot 5.2. If you're using octave 2.1.*, you'll want to get a slightly modified version.
- pgplot_stub.m for pgplot 5.2.
- pgdemo4_for_octave.m, a sample file which calls the pgplot subroutines.
If you have pgplot 5.1, you'll need to get a different pgplot_octave.cc and pgplot_51_stub.m.
Create a .oct file using the mkoctfile script. Various versions of octave have different problems. What you have to do depends on the version of octave:
Version 2.1.* compiled with egcs
Make sure you use the pgplot_octave.cc for version 2.1 (see above). Then issue the command:
```
mkoctfile pgplot_octave.cc -lcpgplot -lpgplot -lX11 -lm
```
Other libraries may be necessary, depending on your system. For example, on my linux system with g77, I found that I had to add an additional library (-lg2c):
```
mkoctfile pgplot_octave.cc -L/usr/X11R6/lib -lcpgplot -lpgplot -lX11 -lg2c -lm
```
Version 2.0.8 and 2.0.9
The mkoctfile script is documented to accept the -llib option but it doesn't work. To fix it, apply the patch contained in the file mkoctfile.patch to the mkoctfile script, like this:
```
cd dir_containing_mkoctfile
patch < mkoctfile.patch
```
(You may need to copy your mkoctfile script into a different directory to apply the patch.)
Now execute mkoctfile like this:
```
mkoctfile pgplot_octave.cc -lcpgplot -lpgplot -lX11 -lm
```
Other libraries may be necessary, depending on your system. (E.g., you might have to add -lf2c or other fortran libraries, especially if octave is linked statically to them. The above works fine for me on Digital Unix 4.0. I'd appreciate comments on what works on other systems.) You may also have to add -L/dir/of/pgplot if you installed pgplot in a nonstandard location.

If you get this to work, I'd appreciate it if you would email me comments on exactly what your system type is, what libraries are necessary for your system, and any tweaks you had to make in compiling pgplot, and any other details or problems you found. This seems to be a difficult step and I currently have access to only one operating system type (linux).
Versions prior to 2.0.8
The mkoctfile script cannot accept additional libraries on the command line. Copy the mkoctfile script and edit it by hand. Change the very last line to read:
```
$SH_LD $SH_LDFLAGS -o $octfile $objfile -lcpgplot -lpgplot -lX11 -lm
```
If you didn't install your pgplot libraries and include files in a standard directory, you'll have to also add -L/your/path/to/pgplot before the -l options in the above line.

Once you've done that, now just type:
```
mkoctfile pgplot_octave
```
Versions prior to 2.0.0
These versions are not supported.
This step should succede in building the file pgplot_octave.oct. Ignore warning messages about _put_pointer and _get_pointer being defined but not used, if they should appear.

Now you're ready to try it. Access it like this:

% setenv PGPLOT_DIR /where/you/put/pgplot
% octave
octave:1> pgplot_stub		# You must do this first.
octave:2> pgopen('/xserv');	# Must specify the output device.
octave:3> pgdemo4_for_octave

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