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diff general/numerical/lambertw.m @ 4:e44f49929e56

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Adding reorganised general toolbox, now in several subdirectories.
author samer
date Sat, 12 Jan 2013 19:21:22 +0000
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/general/numerical/lambertw.m	Sat Jan 12 19:21:22 2013 +0000
@@ -0,0 +1,12 @@
+function W = lambertw(x)
+% lambertw - Lambert's W function
+%
+% lambertw :: real -> real.
+%
+% evaluates W(y) for -1 branch of Lambert W function where
+% y = -exp(-x)
+%
+% The W function satisfies W(t)*exp(W(t)) = t
+
+if x<1, error('lambertw: argument must be >= 1'); end
+W=fixpoint(@(w)(-x-log(abs(w))),-x,'its',60);