Initial data commit

Task/Pythagorean-triples/F-Sharp/pythagorean-triples.fs

@@ -0,0 +1,32 @@
+let isqrt n =
+    let rec iter t =
+        let d = n - t*t
+        if (0 <= d) && (d < t+t+1) // t*t <= n < (t+1)*(t+1)
+        then t else iter ((t+(n/t))/2)
+    iter 1
+
+let rec gcd a b =
+    let t = a % b
+    if t = 0 then b else gcd b t
+
+let coprime a b = gcd a b = 1
+
+let num_to ms =
+    let mutable ctr = 0
+    let mutable prim_ctr = 0
+    let max_m = isqrt (ms/2)
+    for m = 2 to max_m do
+        for j = 0 to (m/2) - 1 do
+            let n = m-(2*j+1)
+            if coprime m n then
+                let s = 2*m*(m+n)
+                if s <= ms then
+                    ctr <- ctr + (ms/s)
+                    prim_ctr <- prim_ctr + 1
+    (ctr, prim_ctr)
+
+let show i =
+    let s, p = num_to i in
+    printfn "For perimeters up to %d there are %d total and %d primitive" i s p;;
+
+List.iter show [ 100; 1000; 10000; 100000; 1000000; 10000000; 100000000 ]