Fast and Robust Curve Intersections

Computes intersection points of two curves.
Updated 31 May 2024

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This function computes the (x,y) locations where two curves intersect. The curves can be broken with NaNs or have vertical segments. It is also very fast (at least on data that represents what I think is a typical application).

Cite As

Douglas Schwarz (2024). Fast and Robust Curve Intersections (, MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R2009a
Compatible with any release
Platform Compatibility
Windows macOS Linux

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Version Published Release Notes

I just learned about the paged matrix functions from Mike Croucher's blog and immediately replaced backslash with pagemldivide for a significant speedup.

This version uses implicit expansion (or bsxfun in slightly older MATLAB versions) to compute the line segments that might overlap. When the number of line segments is large, it uses a different algorithm to avoid forming large matrices.

Fixed bug that my previous "bug fix" failed to fix.

Fixed bug identified by Rodrigo Portugal. No longer fails when there are no intersections and you need 4 outputs.

Added ability to find self-intersections of one curve.