FindMinimum

*To*: mathgroup at smc.vnet.net*Subject*: [mg31134] FindMinimum*From*: Julie RIGAUD <Julie.Rigaud at edf.fr>*Date*: Fri, 12 Oct 2001 03:36:53 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hi ! I have a big problem by using "FindMinimum" to minimize a function which use a simulation software. In fact, i want to minimize this kind of function : g[x]= a - f[x] "a" is a real constant and is well known, but "f" is a sum of command like copy of file and script shell which allow to run my simulation software... At the end, "f " return a real value which must be the best approximated value of "a". So, "f " can't be derivable and i use "FindMinimum" like this : FindMinimum[a-f[x],{x,xstart,xmin,xmax}] Mathematica runs with "xstart" one time but after it stops and says : "FindMinimum::fmgz: Encountered a vanishing gradient. The result returned may not be a minimum; it may be a maximum or a saddle point." I suppose that it is probably due to the HoldAll attribute of FindMinimum but i don't know how to solve this problem ... Can somebody help me ...? Thanks a lot ! Julie