function pdf=dfuni(rangelow, rangehigh, samples) 
% dfuni(rangelow, rangehigh, samples)  Generates a uniform pdf over the  
%    given range.  samples sets the size of the numerical representation,  
%    and is optional.  The default sample size is 1000. 
if nargin==2 
   samples=1000; 
end 
if rangehigh<rangelow 
   error('invalid range') 
end 
R=rangehigh-rangelow; 
x=[rangelow:R/samples:rangehigh]; 
p=ones(length(x), 1); 
C=trapz(x, p); 
p=p./C; 
pdf=[0 1; x' p]; 
if ispf(pdf)==0 
   p=p./ttlprob(pdf); 
   pdf=[0 1; x' p']; 
end