function c = counts(x,v)
% Copyright (c) 2005-2009 by Ales Cerny
%--------------------------------------------------------------------------
% counts(x,v) counts the numbers of elements of vector x that fall into 
% specified ranges determined by vector v.
% 
% Inputs 
%    x   : N*1 vector containing the numbers to be counted.
%    v   : P*1 vector containing breakpoints specifying the ranges within
%          which counts are to be made. v must be sorted in ascending
%          order.
%
% Outputs
%    c   : P*1 vector, the counts of the elements of x that fall into the
%          regions:
%                       x <= v(1),
%                v(1) < x <= v(2),
%                       :
%                       :
%              v(p-1) < x <= v(p).
%--------------------------------------------------------------------------

%************************************************************************%
% counts.m - supplementary program to                                    %
% Ales Cerny (2009) Mathematical Techniques in Finance (2nd ed.)         % 
% Princeton University Press http://press.princeton.edu/titles/9079.html %
%************************************************************************%
    
% This code is provided 'as-is', without any express or implied warranty.  
% 
% Permission is granted to anyone to use this code for any purpose, 
% subject to the following restrictions:
% 
% 1. The origin of this code must not be misrepresented; you must not
%    claim that you wrote the original code.
% 2. Modified code versions must be plainly marked as such, and must not 
%    be misrepresented as being the original code.
% 3. This notice may not be removed from any source distribution.

% NOTICE TO STUDENTS: To avoid accusations of plagiarism, if you use this 
% code or its modifications in assessed work you should prepend it with a 
% note stating: 
%   "This is the original/modified version of the code counts.m by 
%    Ales Cerny (2009), Mathematical Techniques in Finance (2nd ed.),  
%    Princeton University Press. The original version is available from 
%    http://www.martingales.info/mtfweb2".
% A similar acknowledgement should appear prominently inside your written 
% report.

if nargin < 2
    error('Requires at least two input argument.');
end
k = find(v(2:end) - v(1:end-1) <=0);
if any(k)
    error('v must be sorted in ascending order.');
end
temp = zeros(length(v),1);
k = ( x <= v(1));
temp(1) = sum(k);
for i = 2 : length(v)
k = ((x > v(i-1)).*(x <= v(i)));
temp(i) = sum(k);
end
c = temp;