[SciPy-User] How to tell a domain to fmin

[Chris Weisiger]

Er, except that it should have read "if x < 0 or x > 1 or y < 0 or y > 1",
my apologies.

2011/4/16 Chris Weisiger <cweisiger at msg.ucsf.edu>

> You are in control of the cost function passed to fmin. If it wants a value
> outside the domain, you can simply return a very high cost. That should
> effectively constrain the search space to only values inside the desired
> domain. E.g.
>
> def costFunc(coordinates):
>     x, y = coordinates
>     if x < 0 or x > 1 or x < 0 or x > 1:
>         return 10 ** 10
>     return g(x, y)
>
> 2011/4/16 亀田馬志 <masashi.kameda at gmail.com>
>
>> Hello, there.
>> I'm a newbie to scypi, and have stuck around it for a week. Please give me
>> some advice.
>>
>> Suppose I have a formula, geometric mean with logarithm. Let's say I have
>> something like
>>
>> g(x, y) = 0.35*ln|1+4*x+2*y|+0.35*ln|1-x+2*y|+0.3*ln|1-x-y|
>>
>> and want to find its maximum. fmin seems estimated to calculate the
>> minimum, so I just give
>> this formula with negative sign to fmin.
>> fmin told the minimum(actually maximum) of the function. It gives me the
>> result:
>>
>> Out[4]: array([ -5.30653193e-09,   4.00000010e-01])
>>
>> The first element is the negative one. But this is not what I want to get.
>> To be honest, I want to know the maximum in a certain domain, for
>> instance, x >= 0, y >= 0, x + y < 1
>> ; however I don't know how to tell the domain to fmin.
>>
>> I tested some similar geometric means given to fmin, and it sometimes
>> gives "math domain error" or
>> "maximum function evaluates exceeded" because fmin calculates over the
>> area where I estimated, or domain.
>>
>> Please tell me how to tell domain to fmin.
>>
>>
>> --
>> 亀田馬志
>> Masahi Kameda
>>
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>>
>>
>
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