Initial data commit

Task/Forward-difference/Icon/forward-difference.icon

@@ -0,0 +1,17 @@
+procedure main(A)    # Compute all forward difference orders for argument list
+    every order := 1 to (*A-1) do showList(order, fdiff(A, order))
+end
+
+procedure fdiff(A, order)
+    every 1 to order do {
+        every put(B := [], A[i := 2 to *A] - A[i-1])
+        A := B
+        }
+   return A
+end
+
+procedure showList(order, L)
+    writes(right(order,3),": ")
+    every writes(!L," ")
+    write()
+end