X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Finifcns_gamma.cpp;h=bb3a74e0c0a24566bf52fe1ee88d5687bd2f11f7;hp=7bd6669bb8b5eb8c817fd016718c5e3bfdaa2546;hb=f2e7d71e88a82d8f205ce8ca66f51665325585d7;hpb=8d16780dbd9f4da9397e638aca213745589818c0

diff --git a/ginac/inifcns_gamma.cpp b/ginac/inifcns_gamma.cpp
index 7bd6669b..bb3a74e0 100644
--- a/ginac/inifcns_gamma.cpp
+++ b/ginac/inifcns_gamma.cpp
@@ -1,6 +1,7 @@
 /** @file inifcns_gamma.cpp
  *
- *  Implementation of Gamma function and some related stuff. */
+ *  Implementation of Gamma-function, Polygamma-functions, and some related
+ *  stuff. */
 
 /*
  *  GiNaC Copyright (C) 1999 Johannes Gutenberg University Mainz, Germany
@@ -33,7 +34,7 @@
 namespace GiNaC {
 
 //////////
-// gamma function
+// Gamma-function
 //////////
 
 /** Evaluation of gamma(x). Knows about integer arguments, half-integer
@@ -44,7 +45,6 @@ namespace GiNaC {
 static ex gamma_eval(ex const & x)
 {
     if (x.info(info_flags::numeric)) {
-
         // trap integer arguments:
         if ( x.info(info_flags::integer) ) {
             // gamma(n+1) -> n! for postitive n
@@ -87,9 +87,9 @@ static ex gamma_evalf(ex const & x)
 
 static ex gamma_diff(ex const & x, unsigned diff_param)
 {
-    ASSERT(diff_param==0);
-
-    return psi(exZERO(),x)*gamma(x);
+    GINAC_ASSERT(diff_param==0);
+    
+    return psi(exZERO(),x)*gamma(x);  // diff(log(gamma(x)),x)==psi(0,x)
 }
 
 static ex gamma_series(ex const & x, symbol const & s, ex const & point, int order)
@@ -105,7 +105,7 @@ static ex gamma_series(ex const & x, symbol const & s, ex const & point, int ord
 REGISTER_FUNCTION(gamma, gamma_eval, gamma_evalf, gamma_diff, gamma_series);
 
 //////////
-// psi function (aka polygamma function)
+// Psi-function (aka polygamma-function)
 //////////
 
 /** Evaluation of polygamma-function psi(n,x). 
@@ -130,7 +130,7 @@ static ex psi_evalf(ex const & n, ex const & x)
 
 static ex psi_diff(ex const & n, ex const & x, unsigned diff_param)
 {
-    ASSERT(diff_param==0);
+    GINAC_ASSERT(diff_param==0);
     
     return psi(n+1, x);
 }