Optimal Fit: Two Conn. Lines w/ Diff. Slopes

Hello,

If my data are distributed like two lines who intersect i.e. one line goes until some point, and at that point another line emerges with a different slope (they share the same sign).

Is there a way to find

1. equations of each of the lines
2. an estimate of the crossover x-value which lies between each curve
3. a fit goodness measure (Sigma, or chisq?)

I've been looking online for awhile online and I haven't found anything. Any help would be much appreciated.

Thanks,

Michael

Answer 1

[Matt J]

So basically you're looking for a 1st order spline fit? This FEX submission would be applicable

http://www.mathworks.com/matlabcentral/fileexchange/25872-free-knot-spline-approximation

[Michael]

I think this is a complicated solution. Thank you though!