--- a/StatLib.def
+++ b/StatLib.def
@@ -9,6 +9,20 @@
   (*------------------------------------------------------------------------*)
 
   (* $Id: StatLib.def,v 1.4 2015/10/09 07:34:32 mriedl Exp $ *)
+
+PROCEDURE Average(VAR X  : ARRAY OF LONGREAL;
+                      N : CARDINAL) : LONGREAL;
+
+          (*----------------------------------------------------------------*)
+          (* Calculate the average over 'N' values, stored in array 'X'.    *)
+          (*----------------------------------------------------------------*)
+
+PROCEDURE StdDev(VAR X : ARRAY OF LONGREAL;   
+                     N : CARDINAL) : LONGREAL;
+
+          (*----------------------------------------------------------------*)
+          (* Determine the standard deviation of the samples X (N-1 method) *)
+          (*----------------------------------------------------------------*)
 
 PROCEDURE CDF(x : LONGREAL) : LONGREAL;