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# Re: st: could not calculate numerical derivatives

 From Austin Nichols To statalist@hsphsun2.harvard.edu Subject Re: st: could not calculate numerical derivatives Date Tue, 20 Nov 2012 05:55:06 -0500

```vesile kutlu <kutlu.vesile@gmail.com>:
User-written mm_root(); see
http://www.stata.com/statalist/archive/2009-01/msg01140.html

On Tue, Nov 20, 2012 at 5:34 AM, vesile kutlu <kutlu.vesile@gmail.com> wrote:
> Hi all,
> I am trying to solve the function “v” numerically in Mata but I get
> the error ” could not calculate numerical derivatives -- discontinuous
> region with missing values encountered”.  I ask Mata to minimize this
> function with respect to a and b. I provide the initial values of
> these parameters. Is there something wrong with my code? I would
> appreciate if you could tell me why I got this error? Is there maybe
> another way to solve this problem? Thank you.
> Vesile
> void mysolver(todo, p, v, S, H)
>   {
>   a=p[1]
>   b=p[2]
>   v=(0.7-exp((a/b)*(exp(b*48)-exp(b*75))))^2+(0.4-exp((a/b)*(exp(b*48)-exp(b*80))))^2
>   }
>   S=optimize_init()
>   optimize_init_evaluator(S, &mysolver())
>   optimize_init_evaluatortype(S, "v0")
>   optimize_init_params(S, (1,1))
>   optimize_init_which(S, "min")
>   p=optimize(S)
>   p
>   end

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```