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Re: Help with old Mathematica file

  • To: mathgroup at smc.vnet.net
  • Subject: [mg119962] Re: Help with old Mathematica file
  • From: Patrick Scheibe <pscheibe at trm.uni-leipzig.de>
  • Date: Sat, 2 Jul 2011 05:00:43 -0400 (EDT)
  • References: <201107010850.EAA28408@smc.vnet.net>

Hi,

in line 26 and 27 you try to find a minimum of a function z and you are
starting at t=0 which is a maximum. There, the derivative is zero and
FindMinimum doesn't know where to walk. 

Try setting

FindMinimum[z, {t, 0.01, 0, b trif}]

and don't try to adapt the programming style of this book, please.

Cheers
Patrick

On Fri, 2011-07-01 at 04:50 -0400, Zsolt Ero wrote:
> I am trying to solve a problem, for what I finally found a book what has some Mathematica files supplied, but I am stuck now as I cannot run the file.
> 
> My problem is that I cannot run the program as it is written in Mathematica 3.0 and I don't know what should I change to make it run under today's Mathematica versions. Here is the error it returns. 
> 
> > FindMinimum::fmgz: Encountered a
> > gradient that is effectively zero. The
> > result returned may not be a minimum;
> > it may be a maximum or a saddle point.
> 
> The file is called Programs\MOTIPOIN.NB in this file: http://bit.ly/lMQh1K 
> 
> or alternatively, here is a pastebin for the code in question: http://pastebin.com/ASBXnVVS
> 
> Can you have a look at what could be wrong with the code? Its only 50 lines, but I don't know how to fix it.
> 




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