nleU2nu

(rtools/nleU2nu.m)

Function Synopsis

nu=nleU2nu(U)

Help text

function nu=nleU2nu(U)
 converts the normalised log estimator U to the 
 K distribution parameter nu. This does not require numerical
 minimisation, it is a fast iterative algorithm derived for a
 gamma MLE estimate. See gamY2nu.m

 Note, for ensemble averages you are better of using 1/nu - see
 reference [2] below.

 Some references define U as a negative value, this function
 operates on abs(U).

 Needs Matlab R13 for the psi function, otherwise obtain the
 digamma.m file from the net (by Christoph Mecklenbraeuker)

 Source: 
 [1] `Optimum texture estimators for SAR clutter', C.J. Oliver, (1993),
     J. Phys. D: Appl. Phys. 26 p1824-1835
 [2] `Estimation of texture parameters in K-distributed clutter', P. Lombardo,
     C.J. Oliver, (1994), IEE RSN 141(4), p196-204
 [3] `Comparison of parameter estimators for K-distribution', D. Blacknell,
     (1994), IEE RSN 141(1), p45-52

 Part of the Matlab Radar Toolbox v0.11 by Glen Davidson at www.radarworks.com
 Please acknowledge use of this toolbox in any publication or software.
 This header must be retained in any derivative work

Cross-Reference Information

gamY2nu                       rtools/gamY2nu.m

correlation_demo              rtools/correlation_demo.m
k_demo                        rtools/k_demo.m