diff -r 542d2cf143b0 -r 8aaf187d25f0 progs/lecture1.scala
--- a/progs/lecture1.scala	Mon Nov 09 14:36:35 2020 +0000
+++ b/progs/lecture1.scala	Mon Nov 09 17:49:12 2020 +0000
@@ -244,19 +244,21 @@
 /* boolean operators
  
    ==     equals
+   !=     not equals
    !      not
    && ||  and, or
 */
 
 
-def fact2(n: BigInt) : BigInt = 
-  if (n == 0) 1 else n * fact2(n - 1)
 
-fact2(150)
-
-def fib(n: Int) : Int =
+def fib(n: Int) : Int = {
   if (n == 0) 1 else
     if (n == 1) 1 else fib(n - 1) + fib(n - 2)
+}
+
+fib(9)
+
+
 
 
 //gcd - Euclid's algorithm
@@ -278,6 +280,14 @@
 // "last" line (expression) in a function determines the 
 // result
 
+def average(xs: List[Int]) : Int = {
+  if (xs.length == 0) 0 
+  else xs.sum / xs.length
+}
+
+average(List())
+
+
 
 // For-Comprehensions (not For-Loops)
 //====================================