在Mathematica 8中具有等式约束的函数最小化 [英] Function minimization with equality constraints in Mathematica 8

问题描述

在Mathematica 8中使用具有简单等式的约束时，最小化无效.例如.

When using constraints with simple equality in Mathematica 8, minimization doesn't work. E.g.

FindMinimum[{x^2 + y^2,  y == 1}, {x, y}]

在Mathematica 6中可以正常运行，但在版本8中出现错误.其他人可以确认(或解释)吗?看起来像用约束来固定参数之一会使版本8混淆.将xy==1放入也可以，所有不等式也可以.

works ok in Mathematica 6, but gives errors in version 8. Can anyone else confirm (or explain) this? Looks like fixing one of the parameters with a constraint confuses version 8. Putting xy==1 is OK, also any inequality.

对此有任何简单的解决方法吗?我试过更改Method，不走运.我想将所有参数都保留在参数列表中，但是用简单的约束来保存其中一些参数，而不是从列表中删除参数名称.我在版本6中有可用的代码，在版本8中不再可用.

Any simple workaround on this? I have tried changing the Method, no luck. I would like to keep all the parameters in the parameter list, but hold some of them with simple constraint instead of removing the parameter name from the list. I have a working code in version 6, which does not work anymore in 8.

推荐答案

您的语法似乎不正确:

FindMinimum[{x^2 + y^2,  y == 1}, {x, y}]

要求以y开头的x.这对我来说没有多大意义.

which asks to start x with a value of y. This doesn't make much sense to me.

也许您正在尝试做:

Minimize[{x^2 + y^2, y == 1}, {x, y}]

  Out:  {1, {x -> 0, y -> 1}}

---

您的语法显然是有效的.如上所示，考虑将Minimize用作解决您的问题的方法.

---

Apparently your syntax is valid. Consider Minimize as shown above to be a possible work-around for your problem.

这篇关于在Mathematica 8中具有等式约束的函数最小化的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！