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Re: a mathlink question

• To: mathgroup at smc.vnet.net
• Subject: [mg89636] Re: a mathlink question
• From: David Bailey <dave at Remove_Thisdbailey.co.uk>
• Date: Mon, 16 Jun 2008 06:38:04 -0400 (EDT)
• References: <g32q5m$c2t$1@smc.vnet.net>

GS wrote:
> I would like to call a C-program from Mathematica. All the examples in
> the MathLink tutorials (like AddTwo[i,j]) work like this: they are
> called from Mathematica, are executed, send the result to Mathematica
> and exit.
> 
> I would like a C-program to not exit after the execution, and keep the
> memory of the previous inputs. Say, I want an external C-program, to
> be called as AddToPreviousSum[x]. When it is first called, it returns
> x. When it is called the second time AddToPreviousSum[y], it returns x
> +y. When it is called the third time AddToPreviousSum[z], it returns x
> +y+z, and so on.
> 
> How do I implement this in C using MathLink?
> 
> Thanks.
> GS.
> 
Once loaded, your C code remains in memory - think of it as a set of 
functions, and of Mathematica as the main program. Therefore, all you 
need to do, is save information in static or file-scope variables, to be 
used on subsequent calls.

You don't really want the C to keep executing - what would it typically 
do - what you want is for it to stay in memory, which it does.

David Bailey
http://www.dbaileyconsultancy.co.uk