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## Curve Intersect 2

version 1.0 (11 KB) by

Finds the intersection points between two arbitrary polygons.

4.94737
19 Ratings

Updated

General

This file is based on the Curve Intersect function by Duane Hanselman. It extends the scope of the function to handle arbitrary lines / polygons, which may also have vertical segments or segments with non-increasing x-values.

Description
Calculate the intersection points of two 2D-lines / polygons.

Usage
[X,Y]=CURVEINTERSECT(H1,H2) or [X,Y]=CURVEINTERSECT([H1 H2]) or
[X,Y]=CURVEINTERSECT(X1,Y1,X2,Y2) or
-> (H1,H2) handles to line objects
-> (Xi,Yi) coordinates of lines
-> (X,Y) coordinates of intersection

Example
x1=rand(10,1); y1=rand(10,1); x2=rand(10,1); y2=rand(10,1);
[x,y]=curveintersect(x1,y1,x2,y2);
plot(x1,y1,'k',x2,y2,'b',x,y,'ro')

Johannes

### Johannes (view profile)

why does this result in an empty matrix? curveintersect([-1 -0.9],[0 3],[-0.9 0],[3 0])

Daphne

KYAW KYAW

### KYAW KYAW (view profile)

I am looking for the intersection of dynamic waves and base line. SO far, I could manage to get few of the intersection points using ratio (Y data of dynamic wave/ Y data of base line) for whole of samples. Pls advise me how should I continue since I was stuck in here so long.

I used your function but mine is dynamic wave form and base straing line so the X -axis is not constant line. So the array is only (1900x1) for wave form and base line. The Y values of wave form is changing but the base line is seems like constant. Let say, there is 64 intersection points visuality but what i can get is only 47 but some are not accutare positions.

Thanks and best regards
Kyaw

Weylan Yutani

### Weylan Yutani (view profile)

Forgot to say thanks and congrats!

minoo

Zak

### Zak (view profile)

Worked great for me, though my application was quite simple.

Martin Fuchs

### Martin Fuchs (view profile)

Extremly good code ! Thx sharing it !!!

Andreas Lobinger

### Andreas Lobinger (view profile)

One of our students came up with the usage of curveintersect and afaics it works correctly. However the profiler tells me now, that from 300s program runtime 120s are spend in curveintersect and most of the time in the calls to interp1 in curveintersect_l.

Are they really neccessary?

Tyler Jandreau

Yan

### Yan (view profile)

works great! thanks

Nitin

Great job !!

Damir

### Damir (view profile)

It is an excelent job, however I found a bug. The function finds wrong intersection, if one of the curves is almost vertical. Please try this:
x1=[0.1 0.1+1e-17]
y1=[-1 1]
x2=[-1 1]
y2=[-1 1]
[x,y]=curveintersect(x1,y1,x2,y2)
plot(x1,y1,'k',x2,y2,'b:',x,y,'ro')

Carlos G-M

### Carlos G-M (view profile)

Excellent job!! Thanks!

Carlos G-M

### Carlos G-M (view profile)

C. Chaya Boughan

Wonderful program. Worked for some very sticky intensity plots where the points of intersection had been hard to find. Vielen dank Sebastian !!!!

Sathish Athreya

Yes, Obviously it is very fast to find intersection point between curves

David Shepherd

I'm using this to quickly find the point at which two EXIT functions intersect, its perfect thanks mate.

Dick Benson

Overcomes limitations of the D. Hanselman version. THANKS!

Huy Pham

Could we use it for a higher dimension?

leila k

Mat Cop

very useful

Peter Krug

Works well for me

xiaoxu wang

gok gok

great command, thank you!
Are you planning to include the case of infinite line intersection?
Example:
x1=[0 1]; y1=[0 0];x2=[0.5 0.5]; y2=[0.1 1];
will "intersect" at [0.5,0]

 Fixed small bug reported by Vadim Moldavsky
##### MATLAB Release
MATLAB 7.0.1 (R14SP1)