Initial data commit

Task/Forward-difference/NetRexx/forward-difference.netrexx

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+/* NetRexx*************************************************************
+* Forward differences
+* 18.08.2012 Walter Pachl derived from Rexx
+**********************************************************************/
+  Loop n=-1 To 11
+    differences('90 47 58 29 22 32 55 5 55 73',n)
+    End
+
+  method differences(a,n) public static
+  --arr=Rexx[11]                       -- array must be declared (zero based)
+    arr=''                             -- alternative: indexed string
+    m=a.words
+    Select
+      When n<0 Then Say 'n is negative:' n '<' 0
+      When n>m Then Say 'n is too large:' n '>' m
+      Otherwise Do
+        Loop i=1 To m
+          arr[i]=a.word(i)
+          End
+        Loop i = 1 to n
+          t = arr[i]
+          Loop j = i+1 to m
+            u = arr[j]
+            arr[j] = arr[j]-t
+            t = u
+            end
+          end
+        ol=''
+        Loop i=n+1 to m
+          ol=ol arr[i]
+          End
+        Say n ol
+        End
+      End