MATLAB: Interpolation in negative axis

Question

I have fitted my data with a gaussion function. the curve is basically lying in first coordinate and not starting from zero. I want to calculate the value of x for y=0 (x would then definitely come in 2nd coordinate). How to find this value of x. In figure, the first fitted curve (not starting from zero)

fun1 = @(p,xdata) p(1).*(1-exp(-xdata./p(2)))+5000;

I want to a value of x for y=0 (when curve touches x axis). How to find it. Any lead will be appricated.

Answer 1

Once you have your fitted ‘p’ values, you can find the x value at y=0 with the fzero function.

Try this:

fun1 = @(p,xdata) p(1).*(1-exp(-xdata./p(2)))+5000;
x_intercept = fzero(@(xdata) fun1(p,xdata), -1);