diff --git a/matlab/lpdfgbeta.m b/matlab/lpdfgbeta.m
index eeaf4d791..d0c693659 100644
--- a/matlab/lpdfgbeta.m
+++ b/matlab/lpdfgbeta.m
@@ -1,6 +1,26 @@
 function ldens = lpdfgbeta(x,a,b,aa,bb);
+
+% function ldens = lpdfgbeta(x,a,b,aa,bb);
 % log (generalized) BETA PDF 
+%
+% INPUTS
+%    x:      density evatuated at x
+%    a:      BETA distribution paramerer 
+%    b:      BETA distribution paramerer 
+%    aa:     lower bound 
+%    bb:     upper bound 
+
+% OUTPUTS
+%    ldens:  the log (generalized) BETA PDF
+%        
+% SPECIAL REQUIREMENTS
+%    none
+%  
+% part of DYNARE, copyright Dynare Team (2003-2008)
+% Gnu Public License.
+
 ldens = -betaln(a,b) + (a-1)*log(x-aa) + (b-1)*log(bb-x) - (a+b-1)*log(bb-aa);
+
 %gammaln(a+b) - gammaln(a) - gammaln(b)
 %betaln(a,b)
 %pause