1 files changed, 43 insertions, 0 deletions
diff --git a/appl/math/ack.b b/appl/math/ack.b
new file mode 100644
index 00000000..cbed6fdd
--- /dev/null
+++ b/appl/math/ack.b
@@ -0,0 +1,43 @@
+implement Ackermann;
+
+include "sys.m";
+	sys: Sys;
+include "draw.m";
+	draw: Draw;
+
+Ackermann: module
+{
+        init: fn(ctxt: ref Draw->Context, argv: list of string);
+};
+
+init(nil: ref Draw->Context, argv: list of string)
+{
+	sys = load Sys Sys->PATH;
+	draw = load Draw Draw->PATH;
+	argv = tl argv;		# remove program name
+	m := n := 0;
+	if(argv != nil){
+		m = int hd argv;
+		argv = tl argv;
+	}
+	if(m < 0)
+		m = 0;
+	if(argv != nil)
+		n = int hd argv;
+	if(n < 0)
+		n = 0;
+	t0 := sys->millisec();
+	a := ack(m, n);
+	t1 := sys->millisec();
+	sys->print("A(%d, %d) = %d (t = %d ms)\n", m, n, a, t1-t0);	
+}
+
+ack(m, n: int) : int
+{
+        if(m == 0)
+                return n+1;
+        else if(n == 0)
+                return ack(m-1, 1);
+        else
+                return ack(m-1, ack(m, n-1));
+}