Re: Mathematica in conjunction with outside program; NMinimize fails.
- To: mathgroup at smc.vnet.net
- Subject: [mg98947] Re: Mathematica in conjunction with outside program; NMinimize fails.
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Wed, 22 Apr 2009 05:13:38 -0400 (EDT)
- Organization: Uni Leipzig
- References: <gsivfv$9dj$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
Hi,
no the definition is not irrelevant. You just define
SingleModelRun[ parametervalue_?NumericQ ] := ....(definition irrelevant)
and better you write a MathLink program to do the calculation.
Regards
Jens
Andreas Pape wrote:
> Hello mathgroup. I am using Mathematica in conjunction with an
> outside program (Netlogo is the program.) In a nutshell, my error is
> the following: I can call the outside program with a numeric value
> successfully, and Plot can call the outside program as one would
> expect. However, NMinimize calls the outside program with the
> variable name, not a value, so it fails. In short, I need to force
> NMinimize to pass a numeric value to the objective function, not a
> variable name.
>
> More details:
>
> I have the following functions defined in Mathematica:
>
> SingleModelRun[ parametervalue_ ] := ....(definition irrelevant)
> This function (successfully) runs the outside program, setting a
> parameter equal to "parametervalue" (which is some number when I call
> the function). It returns a value from the model.
>
> Plot[ SingleModelRun[ x ], {x , 0, 1} ]
> Does what you expect: runs SingleModelRun for parameter values 0
> through 1, and plots the resulting return value each time.
>
> NMinimize[ - SingleModelRun[ myvalue ], {myvalue} ]
> Does not work. Returns the following error:
>
> NetLogo`Private`NetLogo::"compilerException" : "Nothing named
> MYVALUE has been defined"
>
> (Note: NetLogo is the name of the outside program.)
>
> Which means that, oddly, NMinimize passes the *variable name*
> (myvalue) instead of the *variable value* to the function
> SingleModelRun; otherwise, there is no way the outside program would
> be aware of the variable name.
>
> Is there a way to force Mathematica to evaluate the function with a
> numeric value, not the variable name? (I thought that's what "N" in
> "NMinimize" meant, but apparently not.)
>
> In case you were wondering, this fails in an identical way with:
> NMaximize, FindMaximum, FindMimimum, etc.
>
> Thank you.
>
> Sincerely,
> Andreas Duus Pape
>
>