How can I find and label the intersecting point of two plots?

Hello, I need help finding and labeling the intersect point for a plot of data and a line.

Here is my code:

Vs = 10;
R = 125;
Vd = 0: 1/1000 : 1;
Id = (-1/R)*(Vd)+(Vs/R);
plot (Vd,Id)

hold on
vd = [.86 .847 .819 .770 .75 .729 .6852 .64 .6113]; 
id = [.0914 .06102 .04178 .01964 .01360 .00927 .00423 .00167 .0009389];
plot (vd,id)
hold off

The resulting plot looks like this:

I need to find the point where the two plots intersect and display it some how. Any help is appreciated, Thank you in advance!

Answer 1

[Walter Roberson]

you can interp1 vd id querying at Vd. Take the difference between that and Id and find the place that is closest to 0.

You might need to reverse vd id for interp1 purposes so that vd is ascending

[Elijah Vance]

Would you mind showing my what that would look like in my code? I'm unfimiliar with interp1.

[Walter Roberson]

Vs = 10;
R = 125;
Vd = 0: 1/1000 : 1;
Id = (-1/R)*(Vd)+(Vs/R);
plot (Vd,Id)
hold on
vd = [.86 .847 .819 .770 .75 .729 .6852 .64 .6113]; 
id = [.0914 .06102 .04178 .01964 .01360 .00927 .00423 .00167 .0009389];
plot (vd,id)
hold off

interpolated_id = interp1(vd, id, Vd);
[~, bestidx] = min(abs(Id - interpolated_id));
fprintf('predict a crossing at index #%d where Id is %g and interpolation of id is %g\n', bestidx, Id(bestidx), interpolated_id(bestidx));

predict a crossing at index #853 where Id is 0.073184 and interpolation of id is 0.0727046

Not complete equality; do you need higher precision ?