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 > >