Matlab Spline Interpolation Find X from Y

问题

I need to find the value of x when y = 0.

This is my code:

x=[2,3,4,5,6]; 
y=[10,8,4,1,-2]; 
xi=linspace(2,6,100); 
yi=interp1(x,y,xi,'spline'); 
plot(x,y,'o',xi,yi,'-') 
xlabel('x')
 ylabel('y') 
title('Data')

I tried using fzero, but I couldn't figure out the proper syntax.

I do not have a function f(x) to use, only the points given.

回答1:

A couple of things to note:

1. 'spline' refers to cubic spline. Be absolutely certain that is the interpolation technique that you want. Rerun your code with xi=linspace(0,6,100);

2. The fzero function can be called on the interpolation function:

   fzero(@(xi)interp1(x,y,xi,'spline'),5)
   

来源：https://stackoverflow.com/questions/13319263/matlab-spline-interpolation-find-x-from-y