How to find x value for a given y?

I am trying to find the x value for a specific y value, from a fit. My first guess into how to solve this was:

xval = fzero([cfit - y], x0); 

However this does not work as cfit do not recognize the - sign.

Is there a way to alter the coefficients of the fit I have? Alternatively, is there a simpler function that can be used?

Thanks in advance.

Answer 1

[darova]

Here is an example:

f = @(x) sin(x);
x = 0:10;
x0 = fzero(@(x)f(x)-0.5,pi);
plot(x0,f(x0),'or')
line(x,f(x))

If you have more parameters use thi

x0 = fzero(@(x)f(a,b,x)-0.5, pi);

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