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## Re: Any possible optimization?

 From: Stewart Dickson Subject: Re: Any possible optimization? Date: Mon, 10 Jan 2011 09:41:17 -0600 User-agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.13) Gecko/20101207 Thunderbird/3.1.7

```Are you finding intersections between pairs of line segments in 2-D?
See: U. Murat Erdem -- Fast Line Segment Intersection
http://www.mathworks.com/matlabcentral/fileexchange/27205-fast-line-segment-intersection

It works in Octave.

Cheers,

```
-Stewart, http://us.imdb.com/Name?Stewart+Dickson http://www.ifp.uiuc.edu/~sdickson
```http://emsh.calarts.edu/~mathart/MathArt_siteMap.html

On 1/10/2011 9:15 AM, Daniel Arteaga wrote:
```
```Hi all

```
The following function is called many times in my code (always from the same point), and it is actually the bottleneck of the computation:
```
function [s,t] = intersectionPoint(a,b,c,d)

% Solve the system of equations
% (1 - s) ax + s bx = (1 - t) cx + t dx
% (1 - s) ay + s by = (1 - t) cy + t dy

A = [ b(1) - a(1), c(1) - d(1); b(2) - a(2), c(2) - d(2)];
B = [ c(1) - a(1); c(2) - a(2)];

v = A\B;
s = v(1);
t = v(2);

endfunction

```
Is there any easy way to get a speed increase? Is it worth transforming it into an .oct file? Or maybe including the expressions inline to avoid the function call overhead?
```
Any suggestion is appreciated.

Thank you very much,

Daniel Arteaga

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```