A-M baby

Task/Forward-difference/AWK/forward-difference-2.awk

@@ -0,0 +1,27 @@
+#!/usr/bin/awk -f
+BEGIN {
+   if (p<1) {p = 1};
+}
+
+function diff(s, p) {
+    # pascal triangled with sign changes	
+    b[1] = (p%2) ? 1 : -1;
+    for (j=1; j < p; j++) {
+        b[j+1] = -b[j]*(p-j)/j;
+    };
+
+    n = split(s, a, " ");
+    s = "";
+    for (j = 1; j <= n-p+1; j++) {
+        c = 0;
+        for(i = 1; i <= p; i++) {
+            c += b[i]*a[j+i-1];
+        }
+        s = s" "c;
+    }
+    return s;	
+}
+
+{
+   print diff($0, p);
+}