function [countACGT] = CountACGT(DNA)
%[countACGT] = CountACGT(DNA)
%   Count the number of A,C,G, and T's in the argument DNA and
%   return these counts as a row vector.
%   ($RCSfile: CountACGT.m,v $ $Revision: 1.1.1.1 $)

% sum(DNA=='A') is a Boolean expression and returns a vector of
% length of DNA with 1 and 0 corresponding to whether DNA(i) is
% equal to A or not. Summing the elements of this vector is the
% desired count. 
countACGT=[ sum(DNA=='A') sum(DNA=='C') sum(DNA=='G') sum(DNA=='T')];
return;