While toying with BeOS and looking for neat software for it, I came upon
a library named  Parser created by Ian Russell Ollmann, and  available
at http://wong.scripps.edu/iano/Parser.html.  


A very short quote from Parser's README:


---- begin quote ----
Capabilities:
	This code produces a POEM (Parse Once, Evaluate Many) parser object
which is capable of parsing a numerical expression (such as 3*sin(2+y),
with or without variables, such as "y" in the example just given,
followed by a fast second evaluation step.  As many types of
applications (function plotters, spreadsheets, curve fitters, etc.) 
will often evauate the same expression many, many times, having a fast
second evaluation step which can be called over and over as needed
should help accelerate program execution time. In between each
Evaluate() call, the programmer has the option of changing the value of
any and all variables.  The parser is very quick when evaluating
expressions....
---- end quote ----


If this C++ library could be  incorporated into POV-Ray, then it could
do, without C programming by the artist,  isosurfaces, arbitrary
patterns for pigments and normals, etc (many more ceteras!) 


The library author may be contacted at ian### [at] scrippsedu.  He calls
Parser "community-ware", free for BeOS programming.  Of course, being
C++ is can't be used directly in povray 3.02 or 3.1x patches.  He
requests that he be asked about using Parser in other situations - and I
have already asked, just waiting for his response.  

Ian's web site also lists some other math parser/evaluators.  They all
seem to be either written in Pascal or confined to certain platforms.  
Parser is quasi-platform-independent: Ian says that "Though the Parser
is written in platform independent ANSI C++, users of
little-endian machines (such as x86 IBM-PC clones) should be wary of
possible endian-ness bugs."

So think about this, maybe try using it, maybe write a C equivalent,
maybe wait for povray 4.0, or consider one of the other parsers
mentioned on the Parser web site.

Food for thought, yum yum...

-- 
Daren Scot Wilson
dar### [at] pipelinecom 
www.newcolor.com
----
"A ship in a harbor is safe, but that is not what ships are built for"
                                            -- William Shedd

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On Sat, 02 Jan 1999 14:18:33 +0000, Daren Scot Wilson
<dar### [at] pipelinecom> wrote:

>	This code produces a POEM (Parse Once, Evaluate Many) parser object
>which is capable of parsing a numerical expression (such as 3*sin(2+y),
>with or without variables, such as "y" in the example just given,
>followed by a fast second evaluation step.

The iso patch already functions like this.  The only time you need to
add DLLs is when you want either really fast evaluation, or when your
equation contains conditionals (like the rounded box "function")

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