function lnB = logBetaPDF(x,a,b,c,d)
% logBetaPDF: Calculates the value of the log of the beta distribution.
%
% USAGE:
%
%       lnB = logBetaPDF(x,a,b,c,d)
%
% where c<x<=d is a value of the random vector, while a,b>0 are additional parameters. The output
% vector, lnB, measures the log height of the density of Beta(a,b,c,d).
%
% REQUIRED INPUT:  x (vector) of values between c and d.
%
%                  a (vector) with the a parameter.
%
%                  b (vector) with the b parameter.
%
%                  c (vector) with lower bounds.
%
%                  d (vector) with upper bounds.
%
% REQUIRED OUTPUT: lnB (vector), the log density value at x.
%
%
%                       Written by: Anders Warne
%                                   New Area Wide Model Project
%                                   DG-R/EMO
%                                   European Central Bank (ECB)
%                                   Email: anders.warne@ecb.europa.eu
%                                   Copyright © 2006-2008 European Central Bank.
%
%                       First version: July 23, 2008.
%                        This version: December 18, 2008.
%
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%
% LICENSE INFORMATION:
%
%      YADA is free software: you can redistribute it and/or modify
%      it under the terms of the GNU General Public License as published by
%      the Free Software Foundation, either version 3 of the License, or
%      (at your option) any later version.
%
%      This program is distributed in the hope that it will be useful,
%      but WITHOUT ANY WARRANTY; without even the implied warranty of
%      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%      GNU General Public License for more details.
%
%      You should have received a copy of the GNU General Public License
%      along with this program.  If not, see <http://www.gnu.org/licenses/>.
%
%      YADA is released under the GNU General Public License, Version 3,
%      29 June 2007 <http://www.gnu.org/licenses/>. The current release of
%      the program was last modified by the ECB on the "This version" date
%      above.
%
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%
% CHANGELOG:
%
% * 18-12-2008: Updated the documentation.
%
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%

z = (x-c)./(d-c);
lnB = -log(d-c) - betaln(a,b)+((a-1).*log(z))+((b-1).*log(1-z));

%
% end of logBetaPDF.m
%
