Computing the inverse of function in MATLAB

Question

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?

Answer 1

Numerical inverse of a monotone Function: let v be a monotone ascending array of numbers (that means v=sort(v)). Then you can derive the inverse (vinv) very simple:

vinv=cumsum(hist(v,length(v)));

After this you can beautify the result with a bit of scaling, but basically the cumsum of hist -thingi does the trick.

You can test the following:

x=randn(1,1000);
v=sort(x);
plot(v);
vinv=cumsum(hist(v,1000));
figure(2);
plot(vinv);