在MATLAB中计算函数的逆函数 [英] Computing the inverse of function in MATLAB

问题描述

如何在MATLAB中计算函数的逆函数?假设您要计算f(x)= e ^ x的逆，那么代码是什么?

How do you compute the inverse of a function in MATLAB? Say you want to compute the inverse of f(x)=e^x, what would be the code?

推荐答案

如果分析方法失败(在可能的情况下首选)，请使用数值方法:

If the analytical approach fails (which is preferred whenever possible) use numerical approach:

给出y并求出x0的倒数

Given y and guess x0 for the inverse

x = fzero( @(x)(f(x)-y), x0 ); 

或者当x的范围已知为xmin ... xmax时使用低精度但较快的方法

or a low accuracy but faster method when the range of x known to be bounded in xmin...xmax

xx = linspace( xmin, xmax, N );
yy = f(xx);
x = interp1(yy, xx, y);

当然，必须根据所需的精度选择N.

Of course, N has to be chosen according to the desired accuracy.

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