# Find intersection of points in a graph

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Chinmayraj Doddarajappa on 8 Jul 2022
Answered: Hrusheekesh on 11 Jul 2022 Is there a way to find the intersection of two curves in the graph? If yes, can someone help me with the code

Star Strider on 8 Jul 2022
It would help to have the actual data. Assuming that ‘y2’ is either a constant or a line defined as a function of the same independent variable values as ‘y1’, this is straightforward —
x = linspace(0, 9); % Independent Variable
y1 = 700*exp(-0.45*x); % Curve
y2 = 150; % Line
xint = interp1(y1-y2, x, 0) % X-Intercept (Interpolation)
xint = 3.4236
figure
plot(x, y1, [0 9], [1 1]*y2, xint, y2, 'sr')
legend('y_1', 'y_2', 'Intersection', 'Location','best')
text(xint, y2, sprintf(' \\leftarrow Intersection: X = %.3f',xint), 'Horiz','left', 'Vert','middle', 'Rotation',30) See the documentation on the interp1 function for details.
If both lines are defined on different independent variable values, a separate intermediate interpolation to define them with respect to the same independent variable vector (using interp1) would be required first.
.
##### 2 CommentsShowHide 1 older comment
Star Strider on 8 Jul 2022
As always, my pleasure!

### More Answers (2)

KSSV on 8 Jul 2022
You can consider using this:
##### 1 CommentShowHide None
Chinmayraj Doddarajappa on 8 Jul 2022
Thank you

Hrusheekesh on 11 Jul 2022
Hi chinmayraj,
You can refer to this page to find the intersection of two curves.
You can also subtract the two curves and get the absolute difference, compare with the tolerance (ex: eps) for near values.

R2021b

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