在MATLAB中求解指数方程 [英] Solving Exponential equation in MATLAB

问题描述

我现在正在尝试在MATLAB中求解指数方程式，这是我的作业的一部分.很容易看到方程式

I am now trying to solve an exponential equation in MATLAB as a part of my assignment. It is easy to see that the equation

exp(-t)+t*exp(-t)-n=0

将有两种解决方案，一种大于零，一种较小.

would have two solutions, one greater than zero and one smaller.

但是，仅使用Solve函数，MATLAB返回一个称为lambertw函数，它只能将eval()返回零以下的解，而这恰恰不是我想要的答案.有人可以在这里帮助我吗?

However, using just the solve function, MATLAB returns something called lambertw function and it can only eval() to the solution below zero, which happens not to be the one I want for the answer. Could anyone help me here?

提前感谢所有答案和评论！

Thanks in advance for all the answers and comments!

p.s.作为替代方案，我正在考虑使用Newton-Raphson方法来解决它，但是我想知道与Solve()相比，速度如何?

p.s. As an alternative, I am thinking about using Newton-Raphson method to solve it, but I wonder how is the speed comparing to solve()?

子尧伟

推荐答案

lambertw是您需要的功能.但是，它是一个多值函数，并且具有多个分支.您需要选择正确的分支来回答.参见另一个问题，关于如何为解决方案选择其他分支.

lambertw is the function that you need. However, it is a multivalued function and has several branches. You need to choose the right branch for your answer. See my answer to another question on how to choose a different branch for the solution.

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