function [U] = KummerUz(a,b,z);
% 02.06.2014

%  This function computes the Tricomi confluent hypergeometric function U(a,b,z)
%  by using the method described by Abad and Sesma, for non-integer b

%%  'z' can be a vector

U = gamma(1-b)*KummerMz(a,b,z)/gamma(a-b+1) + gamma(b-1)*z.^(1-b).*KummerMz(a-b+1,2-b,z)/gamma(a);
  