Add documentation on code origin, clarify status.

README.md

@@ -20,10 +20,10 @@ The resulting slope and offset are the median slope and offset of the lines defi
 
 ### No toolbox required
 
-This code is based on [Theil-Sen Robust Linear Regression](https://mathworks.com/matlabcentral/fileexchange/48294-theil-sen-robust-linear-regression), version 1.2.0.0, by Zachary Danziger.
-A key modification is to use `median(X, 'omitnan')` instead of `nanmedian(X)` to avoid dependency on the (commercially licensed) [Statistics Toolbox](https://mathworks.com/products/statistics.html).  
-(Note that there are several other implementations on Mathworks's [File Exchange](https://mathworks.com/matlabcentral/fileexchange).
-Unfortunately, most were found to depend on the Statistics Toolbox, [except one](https://mathworks.com/matlabcentral/fileexchange/43135-regression-utilities), which was judged to be slower and less versatile.)
+This code is based on [Theil-Sen Robust Linear Regression](https://mathworks.com/matlabcentral/fileexchange/48294-theil-sen-robust-linear-regression), version 1.2.0.0, by Zachary Danziger (which in turn is based on [Theil–Sen estimator](https://de.mathworks.com/matlabcentral/fileexchange/34308-theil-sen-estimator), version 1.0.0.0 by Arnout Tilgenkamp).
+Note that these previous versions depend on the (commercially licensed) [Statistics Toolbox](https://mathworks.com/products/statistics.html).
+
+This version uses `median(X, 'omitnan')` instead of `nanmedian(X)` to avoid dependency on the Statistics Toolbox.
 
 See the [changelog](#changelog) below for further modifications.
 
@@ -47,23 +47,24 @@ Note how a few "unlucky" outliers can bias the least squares estimate (LS), but
 
 ## Changelog
 
-- October 2014 by Z. Danziger: Original version.
+- December 2011 by A. Tilgenkamp: Release of version 1.0.0.0 on Mathworks File Exchange.
 - September 2015 by Z. Danziger: Updated help, speed increase for 2D case
 - March 2022 by J. Keyser: Adjusted formatting, added documentation, improved example and added plot, replaced `nanmedian(X)` with `median(X, 'omitnan')`, removed 2D special case, restructured input and output parameters.
 - August 2022 by J. Keyser: Explicit omission of identical x coordinates, added coefficient of determination (unadjusted R²) as optional output.
+- August 2023 by J. Keyser: Add documentation about original author of version 1.0.0.0.
 
 ## Contributing and project status
 
-This project is relatively unmaintained.
+This project is considered complete and is relatively unmaintained.
 It is shared as-is in the hope to be helpful (see [license.txt](license.txt) for legal terms).
 
-If you find a bug, feel free to let the author(s) know.
-Feature requests should be directed to the original author (see below).
+If you find a bug, please let the author(s) know.
 
 ## Authors
 
-1. Zachary Danziger, original author ([Matlab profile](https://de.mathworks.com/matlabcentral/profile/authors/1044524), [lab webpage](https://anil.fiu.edu/))
-2. Johannes Keyser
+- Arnout Tilgenkamp ([Matlab profile](https://mathworks.com/matlabcentral/profile/authors/1561419))
+- Zachary Danziger ([Matlab profile](https://de.mathworks.com/matlabcentral/profile/authors/1044524)
+- Johannes Keyser ([Matlab profile](https://mathworks.com/matlabcentral/profile/authors/2267277))
 
 ## License