quoted from:https://csdms.colorado.edu/wiki/Model:Chi_analysis_tools
This code has been developed by the University of Edinburgh Land Surface Dynamics group to analyse channel longitudinal profiles using the integral method of channel analysis. The integral method is a means of comparing the relative steepness of channel profiles, normalized for drainage area. It is similar to, but has some advantages over, traditional slope area analysis. See Perron and Royden (2013) for more details on the integral method.
This particular code not only transforms channels using the integral method, but it also uses statistical techniques to find the most likely series of channel segments with distinct steepness and the most likely m/n ratio. The details of these algorithms can be found in Mudd et al. (submitted manuscript) which is available here: http://www.geos.ed.ac.uk/homes/smudd/Muddetal_JGRsubmit.pdf.
The code consists of objects that contain topographic data and their member functions, and driver programs perform the analyses. Full documentation is available under the ‘other’ tab in the wiki.
Reference: Perron, J.T. and L. Royden (2013). An integral approach to bedrock river profile analysis. Earth Surface Processes and Landforms, 38, 570-576, doi:10.1002/esp.3302.