function y=lght(b,x)

%LGHT (light) opposite of the function HEAVY
%   
%   LGHT(a,x) returns the value 1 if x<a and 
%   the value 0 if x>a.  If x=a the value 0.5
%   is returned.
%
%   LGHT(a,x) may be thought of as a function
%   of x, with parameter a.  The function 
%   jumps from 1 to 0 at the value a.
%
% Record of Revisions:
%
%        Date       Description
%        ====       ===========   
%  0. 22-Jan-2001   File created. (DGCH)
%  1. 07-Feb-2001   Comments added. (DGCH)
%


y = ( sign(b-x) + 1 )./2;