需要帮助理解 Apache Commons Math BracketFinder
我首先要说的是，这感觉应该很容易……但对我来说并不完全明显。我正在尝试使用 BrentOptimizer 来查找函数的局部最小值和最大值。我知道这些的周期性，我觉得我应该能够使用 BracketFinder 将最优值括起来，然后将其发送到 BrentOptimizer。
因此，对于一个简单的情况，请考虑：
f(x) = sin(x)
我们知道最大值位于 Pi/2 处，最小值位于 3Pi/2 处。如果我从零开始并沿着函数移动，我将如何寻找 Pi/2 处的根？它实际上取决于构造函数参数和初始点。是否有任何最佳实践（假设您对函数的形状有所了解）可以用来以合理的方式设置这些参数？
谢谢
I will start off by saying that this feels like it should be easy... but it's not entirely obvious to me. I am trying to use the BrentOptimizer to find local minima and maxima of a function. I have an idea of the periodicity of these, and I feel like I should be able to use the BracketFinder to bracket the optimums and then send that off to the BrentOptimizer.
Her is the documentation: http://commons.apache.org/math/api-2.2/org/apache/commons/math/optimization/univariate/BracketFinder.html
So for a simple case, consider:
f(x) = sin(x)
We know that there is a max at Pi/2 and a min at 3Pi/2. If I were starting at zero and moving along the function, how would I go looking for that root at Pi/2? It really comes down to the constructor arguments and the initial points. Are there any best practices (assuming you know a little bit about the shape of your function) that I can use to set these parameters in a reasonable way?
Thanks
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您现在可能已经解决了这个问题，但是括号方法根本不需要任何初始点，
BracketFinder的目的是找到一个开始猜测，您应该在调用 BrentOptimizer。在BracketFinder中应用默认构造函数应该没问题。收到包围点后，使用三点
optimize抽象基类中定义的方法 BaseAbstractUnivariateOptimizer，其中min，max、startValue取自BracketFinder：sgetLo()、getHi() 和getMid()。BracketFinder 实现显然是基于 数值食谱，本书 C 版本中的第 10.1 章。这可以为您提供有关所使用的包围原则的更多背景知识。
You have probably sorted this out by now, but the bracketing method does not expect any initial points at all, the intention with
BracketFinderis to find a starting guess that you should apply in your call to the BrentOptimizer. It should be OK to apply the default constructor inBracketFinder.After having received bracketing points, use the three-point
optimizemethod defined in the abstract base class BaseAbstractUnivariateOptimizer, wheremin,max,startValueare taken from theBracketFinder:sgetLo(),getHi()andgetMid(), respectively.The BracketFinder implementation is obviously based on the one found in Numerical Recipes, chapter 10.1 in the C version of the book. This could give you some more background on the bracketing principles used.