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MathGroup Archive 2006

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Re: why does FindMinimum have the attribute HoldAll?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg69895] Re: why does FindMinimum have the attribute HoldAll?
  • From: "Chris Chiasson" <chris at chiasson.name>
  • Date: Wed, 27 Sep 2006 06:03:48 -0400 (EDT)
  • References: <acbec1a40609260710p5fdd6302u15c87af79eae3d2b@mail.gmail.com>

Actually, with FindMinimum it's a little more complicated than what I
said because I think it has some kind of heuristic to realize when the
first argument isn't a numeric function in held form - then
FindMinimum evaluates the argument to make the optimization work. I
guess that is for compatibility with old code. However, the heuristic
doesn't work if there is an option present.

For example:

In[1]:=
fun=x^2+y^2;

In[2]:=
opt=Method->"Gradient";

In[3]:=
guesses={{x,1},{y,2}};

In[4]:=
FindMinimum[fun,guesses]

Out[4]=
{0.,{x\[Rule]0.,y\[Rule]0.}}

In[5]:=
FindMinimum[fun,guesses,opt]

From In[5]:=
FindMinimum::"fdssnv" : Search specification guesses without variables
should be a list with a 1-4 elements.

Out[5]=
FindMinimum[fun,guesses,opt]

Maybe I should just have started with Plot, but I hope I got the
original question across.

On 9/26/06, Chris Chiasson <chris at chiasson.name> wrote:
> instead of the attribute HoldFirst?
>
> HolAll makes it a pain to dynamically populate the variables and their
> initial values. I usually end up Blocking FindMinimum so that I can
> get the call right.
>
> I have a similar question about Plot, but I figured I'd ask one at a time.
>
>
>
> --
> http://chris.chiasson.name/
>


-- 
http://chris.chiasson.name/


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