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Re: st: Optimize
From
Austin Nichols <[email protected]>
To
[email protected]
Subject
Re: st: Optimize
Date
Mon, 23 Jul 2012 10:25:57 -0400
Mohamud Hussein <[email protected]>:
Looks like you are trying to maximize the unbounded quadratic rather
than find its zeros. Use a root finder instead e.g.
http://www.stata.com/statalist/archive/2007-12/msg00551.html
http://www.stata.com/statalist/archive/2009-01/msg01140.html
but note first that the particular example you gave has no zeros (so
no interior solution).
On Sun, Jul 22, 2012 at 9:59 AM, Mohamud Hussein
<[email protected]> wrote:
> Hi there,
>
> I am trying to run a model for a marginal cost curve equation based on the traditional cubic total cost curve function (i.e. y= x^3+X^2+X+c) using Stata's optimize() command. The goal is to estimate the value of x which minimises y subject to a number of constraints.
>
> When I tried to specify the marginal cost curve function in mata directly as y=3x^2+2x+1 (i.e. first derivative of the total cost equation) I got the following message:
>
> Iteration 0: f(p) = 1 (not concave)
> Iteration 1: f(p) = 7.911e+71 (not concave)
> Iteration 2: f(p) = 1.95e+169 (not concave)
> Iteration 3: f(p) = 8.32e+250 (not concave)
> Iteration 4: f(p) = 1.62e+288 (not concave)
> Iteration 5: f(p) = 2.34e+306
> Hessian is not negative semidefinite
>
> I have never used Stata's mata programming language before and am not quite sure of what do here? Grateful if someone can help me on this.
>
> Thanks,
> Mohamud
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