2016 Update

Task/Arithmetic-geometric-mean/Clojure/arithmetic-geometric-mean.clj

@@ -0,0 +1,25 @@
+(ns agmcompute
+  (:gen-class))
+
+; Java Arbitray Precision Library
+(import '(org.apfloat Apfloat ApfloatMath))
+
+(def precision 70)
+(def one (Apfloat. 1M precision))
+(def two (Apfloat. 2M precision))
+(def half (Apfloat. 0.5M precision))
+(def isqrt2 (.divide one  (ApfloatMath/pow two half)))
+(def TOLERANCE (Apfloat. 0.000000M precision))
+
+(defn agm [a g]
+  " Simple AGM Loop calculation "
+       (let [THRESH 1e-65                 ; done when error less than threshold or we exceed max loops
+             MAX-LOOPS 1000000]
+        (loop [[an gn] [a g], cnt 0]
+            (if (or (< (ApfloatMath/abs (.subtract an gn)) THRESH)
+                    (> cnt MAX-LOOPS))
+              an
+              (recur [(.multiply (.add an gn) half) (ApfloatMath/pow (.multiply an gn) half)]
+                     (inc cnt))))))
+
+(println  (agm one isqrt2))