How to know x value if I have y value from graph

Hi all, I have fitted the curve, and plot it.

Now, I have y value, it equal to 100 (y=100),

how to extract x value from fitting curve? Because original data do not have x value when y=100.

Thank you

Answer 1

[Arun Mathamkode]

I assume you will have the model which you used to fit the data and the coefficients. You can invert the model and find X from Y.

The following answer also will be helpful to you.

https://www.mathworks.com/matlabcentral/answers/181251-how-can-i-find-x-for-given-y-value-in-a-fitted-curve