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Re: easiest way to display a plot from C to kernel using Mathlink?

• To: mathgroup at smc.vnet.net
• Subject: [mg22386] Re: easiest way to display a plot from C to kernel using Mathlink?
• From: paulh at wolfram.com (P.J. Hinton)
• Date: Sun, 27 Feb 2000 18:55:26 -0500 (EST)
• Organization: "Wolfram Research, Inc."
• References: <897eon$5to@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

In article <897eon$5to at smc.vnet.net>,
 dave linenberg <dlinenbe at home.com> writes:

> I am interested in using Mathlink to display plots, calling it
> externally.
> 
> I am calling the Mathematica 4.0 kernel via C function calls in my own
> program using Linux (Redhat 6.0)
> 
> I have searched the newsgroups for the last few years, and have not
> found much information.
> I have Gayley's Mathlink tutorial, but it falls apart in addressing the
> display of postscript files or graphics when
> calling the Mathematica kernel from external programs. (No examples).
> 
> I would like to know -
>     * how to generate postscript files using C code w/ Mathlink /
> Mathematica 4.0 Linux Redhat 6.0, gcc/g++

The easiest way to generate pure PostScript files is to pipe the
output of Display[] through a shell script called psfix.  psfix 
is still installed by the Unix installers, but it resides in a
directory that does not appear on the shell's PATH setting.  You
should be able to find it in:

<path to Mathematica installation>/SystemFiles/Graphics/SystemResources

The comments in the script provide information on the command line
flags that you can supply.  You can also use the comments in the 
script to learn more about how abbreviated Mathematica PostScript
operators map to actual Adobe PostScript.

>     * as well as ... how to automatically open a separate window to
> display such graphics

You could write your own PostScript interpreter and renderer, or you
could use motifps.  You use Display[] to write the abbreviated 
Mathematica PostScript to a scratch file and then call a wrapper
shell script to launch the motifps binary.  You will need to adjust
the topdir variable to reflect the actual path to the Mathematica
installation on your system.

[begin sample shell script]
#!/bin/sh

topdir=/usr/local/mathematica/4.0.1
sysid=Linux
bindir=$topdir/SystemFiles/Graphics/Binaries/$sysid

PATH=bindir:$PATH
export PATH

XFILESEARCHPATH=$topdir/SystemFiles/Graphics/TextResources/English/%N
export XFILESEARCHPATH

if [ ."$PSRESOURCEPATH" = . ]; then
   PSRESOURCEPATH=$topdir/SystemFiles/Graphics/SystemResources:$topdir/SystemFiles/Fonts/Type1
else
   PSRESOURCEPATH=$PSRESOURCEPATH:$topdir/SystemFiles/Graphics/SystemResources:$topdir/SystemFiles/Fonts/Type1
fi
export PSRESOURCEPATH

exec $bindir/motifps $@          
[end sample shell script]

The PSRESOURCEPATH variable is a list of directories where PostScript
resource files (Type 1 fonts, procesets, etc.) reside.  You can 
add your own Type 1 font directories to this list, provided that you
generate a PostScript resource catalog (PSres.upr) with the makepsres
utility in SystemFiles/Graphics/Binaries/Linux.  

-- 
P.J. Hinton
Mathematica Programming Group           paulh at wolfram.com
Wolfram Research, Inc.
Disclaimer: Opinions expressed herein are those of the author alone.