view general/numerical/scalar/lambertw.m @ 29:61921dceded1

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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);