How to evaluate the x value corresponding to an y value from a plotted y(x)?

I am trying to evaluate the x value corresponding to an y value, after plotting y(x). How can I do that for any kind of values? I used the find function, but it fails. I attached the code lines below:

% parameters
mu0 = pi*4e-7;  
M = 1.3e5;
R = 0.5e-6;
H = 0.67e-6;
d = [1e-6:1e-7:1e-5];

% function definition
format long;
F = (1./4)*(pi*mu0*M^2*R^4)*(1./d.^2+1./(d+2*H).^2-2./(d+H).^2);

% plot F(d)
plot(d,F,'green', 'LineWidth', 2);

% evaluating the x of an y (the d value corresponding to an F)
index = find(F == 1e-10)
d_coresp = d(index)

Answer 1

[Azzi Abdelmalek]

Dont use

 index = find(F == 1e-10)

use

 eror=1e-11
 [~,idx]=find(abs(F-1e-10)> eror 
 % eror depends on how many samples you are using and on the variation of F

your are not sur 1e-10 belongs to your plot

[Agent Cooper]

Dear Azzi,

I tried to follow you suggestion but I get the following error message:

"Error using >

Too many output arguments."

Any idea on how could this be fixed?

[Azzi Abdelmalek]

Sorry for the wrong comment. can you post a sample of your data?

[Azzi Abdelmalek]

Ok I missed one ) .

eror=1e-11
[idx,~]=find(abs(F-1e-10)> eror)

[Azzi Abdelmalek]

[idx,~] instead of [~,idx]