Why Matlab does not have a fmaxsearch?

Question

Bernardino 2013-11-3

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https://ww2.mathworks.cn/matlabcentral/answers/104765-why-matlab-does-not-have-a-fmaxsearch

评论： Walter Roberson 2024-3-4

采纳的回答： Matt J

I know that Matlab has a fminsearch, but why it does not have a fmaxsearch?

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Dainery 2024-3-4

Matlab tiene una función llamada fminsearch, pero no tiene una función llamada fmaxsearch. La razón probable por la que no existe una función fmaxsearch es porque generalmente en problemas de optimización se busca minimizar una función objetivo en lugar de maximizarla. En el caso de querer encontrar el máximo de una función en Matlab, se puede simplemente multiplicar la función por -1 y utilizar fminsearch para encontrar el mínimo de la función negativa. De esta manera se obtendrá el máximo de la función original.

Walter Roberson 2024-3-4

Approximate translation:

Matlab has a function called fminsearch, but it does not have a function called fmaxsearch. The likely reason why there is no fmaxsearch function is because optimization problems generally seek to minimize an objective function rather than maximize it. If you want to find the maximum of a function in Matlab, you can simply multiply the function by -1 and use fminsearch to find the minimum of the negative function. In this way the maximum of the original function will be obtained.

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Answer 1

Matt J 2013-11-3

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https://ww2.mathworks.cn/matlabcentral/answers/104765-why-matlab-does-not-have-a-fmaxsearch#answer_114020

编辑：Matt J 2013-11-3

Because you can easily convert a maximization problem to a minimization problem just by multiplying the function by -1.

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Matt J 2022-11-12

No, I meant how I phrased it originally, but both are true.

Walter Roberson 2022-11-13

if you need to do a minimization and all you have available is a minimization function, use that
if you need to do a maximization and all you have available is a maximization function, use that
if you need to do a minimization and all you have available is a maximization function, then maximize the negative of the function you need to minimizat
if you need to do a maximization and all you have available is a minimization function, then minimize the negative of the function you need to maximize

MATLAB only provides minimization functions (except for Problem Based Optimization, you can tell those to maximize), so if you need to minimize use one of the minimization functions, and if you need to maximize then use one of the minimization functions on the function you need to maximize.

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