Put a reference on eta function into tutorial.

diff --git a/doc/tutorial/ginac.texi b/doc/tutorial/ginac.texi
index fa0d4bd4f0d26e7dce9d8fe1064106a28bbc357c..21e31b2c98501fc7581ceed6c3013e978dbbc3f1 100644 (file)
--- a/doc/tutorial/ginac.texi
+++ b/doc/tutorial/ginac.texi
@@ -5858,6 +5858,9 @@ GiNaC contains the following predefined mathematical functions:
 @item @code{log(x)}
 @tab natural logarithm
 @cindex @code{log()}
 @item @code{log(x)}
 @tab natural logarithm
 @cindex @code{log()}

+@item @code{eta(x,y)}
+@tab Eta function: @code{eta(x,y) = log(x*y) - log(x) - log(y)}
+@cindex @code{eta()}

 @item @code{Li2(x)}
 @tab dilogarithm
 @cindex @code{Li2()}
 @item @code{Li2(x)}
 @tab dilogarithm
 @cindex @code{Li2()}