       Re: Two successive FindMinimum -> Bug?

• To: mathgroup at smc.vnet.net
• Subject: [mg74329] Re: [mg74312] Two successive FindMinimum -> Bug?
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Mon, 19 Mar 2007 01:56:44 -0500 (EST)

```fxt[x_,t_]=(x^2-t)^2;

Reduce[fxt[x,t]==0,t]

t == x^2

tminx should be restricted to numeric arguments

tminx[x_?NumericQ]:=t/.FindMinimum[fxt[x,t],{t,1}][];

tminabs=FindMinimum[tminx[x],{x,1}]

{0., {x -> 7.450580485901526*^-9}}

Bob Hanlon

---- Dmitry Garanin <dgaranin at yahoo.com> wrote:
> Hi All,
>
> I am trying to solve a problem that requires application of FindMinimum (or similar rutines two times and it does not work. Here is a simplified example:
>
>
> fxt[x_,t_]=(x^2-t)^2  (* Searching for a minimal t for which fxt turns to zero *)
> tminx[x_]:=t/.FindMinimum[fxt[x,t],{t,1}][] (* Finding the minimizing t for a given x *)
> tminabs=FindMinimum[tminx[x],{x,1}]  (* Minimizing this t with respect to x. The result should be tminabs=0 at x=0 *)
>
> The last command here does not work since, evidently tminx[x] (that is x^2 for us humans) is not treated as a regular function.
>
> Is there a bug here or I am doing something wrong??
>
> Help is appreciated.
>
>
> http://profiles.yahoo.com/dgaranin
>

```

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