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MathGroup Archive 1999

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Re: FindMinimum

  • To: mathgroup at
  • Subject: [mg15840] Re: FindMinimum
  • From: Mark Fisher <mefisher at>
  • Date: Fri, 12 Feb 1999 18:40:00 -0500 (EST)
  • References: <79m6o0$>
  • Sender: owner-wri-mathgroup at


one way to handle the problem is to put your function into an If
statement that returns a huge number when its out of bounds

newfun[x_, y_] := If[Abs[x] > 1 || Abs[y] > 1, 10^10,
    oldfun[x, y]]


Hossein Kazemi wrote:

> I have an expression that involves the Sign[] function.  For example,
> consider
> f=Sign[4.35x-13.57y +(1-x^2-y^2)]-Sign[2.49x-11.18y+(1-x^2-y^2)]+...
> I need to find the minimum of this function.  Since the symbolic
> derivatives with respect to x and y do not exist, I have to use
> FindMinimum[f,{x,{x0,x1}},{y,{y0,y1}}]
> But this does not restrict Mathematica not look outside (-1,1) range for
> solutions,
> where (1 - x^2 - y^2) will not be real.
> Is there anyway to find the minimum of a function when symbolic
> derivatives of
> the function do not exist and values outside a range should not be used.
> Thank you.
> kazemi at som.umass.edi

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