function out = unit(t)
%  This function is the unit step:
%
%   sig = unit(t), where SIG and T are vectors of the same dimension.
%
%   elements of out are either 0 or 1 corresponding to elements of T
%   being negative or non-negative, respectively.
%
%
%        written by Kevin D. Donohue   2/93
%
out = zeros(size(t));             %  Initialize output array to zeros
elm_1 = find(t >= 0);             %  Find positive values on t-axis
out(elm_1) = ones(size(elm_1));