Re: typing starting values in FindMinimum
- To: mathgroup at smc.vnet.net
- Subject: [mg15446] Re: typing starting values in FindMinimum
- From: Robert Knapp <rknapp>
- Date: Mon, 18 Jan 1999 04:21:48 -0500
- Organization: Wolfram Research, Inc.
- References: <77f0j5$m17@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Albert Maydeu-Olivares wrote:
>
> Hi everyone,
>
> Consider the use of FindMinimum when the function to be minimized
> depends on several variables
>
> In[1]:=
> j={{l2,l1,0},{l3,0,l1},{0,l3,l2}};
> e={0.56 -l1 l2,0.48 -l1 l3, 0.42 -l2 l3};
> FindMinimum[Apply[Plus,e^2],{l1,.5},{l2,.5},{l3,.5},Method->Newton,
> Gradient->j]
>
> Out[1]=
> {8.68919*^-23, {l1->.8, l2->.7, l3->.6}}
>
> Does anyone know to avoid having to type in all the variables names and
> starting values?
> I have some problems with 100 variables!
>
> Of course I can construct
>
> In[3]:=
> theta={l1,l2,l3};
> start ={0.5,0.5,0.5};
> startval=Transpose[{theta,start}]
>
> Out[3]:=
> {{l1,0.5},{l2,0.5},{l3,0.5}}
>
> but that is not what FindMinimum is expecting.
>
All you need to do is use
FindMinimum[Apply[Plus,e^2],Evaluate[Apply[Sequence, startval]],
Method->Newton,Gradient->j]
The evaluate is necessary because FindMinimum does not by default
evaluate its arguments.