Data commit

Task/Arithmetic-geometric-mean/Lambdatalk/arithmetic-geometric-mean.lambdatalk

@@ -0,0 +1,31 @@
+{def eps 1e-15}
+-> eps
+
+{def agm
+  {lambda {:a :g}
+   {if {> {abs {- :a :g}} {eps}}
+    then {agm {/ {+ :a :g} 2}
+              {sqrt {* :a :g}}}
+    else :a }}}
+-> agm
+
+{agm 1 {/ 1 {sqrt 2}}}
+-> 0.8472130847939792
+
+Multi-precision version using the lib_BN library
+
+{BN.DEC 70}
+->   70 digits
+{def EPS {BN./ 1 {BN.pow 10 45}}}
+-> EPS
+
+{def AGM
+  {lambda {:a :g}
+   {if {= {BN.compare {BN.abs {BN.- :a :g}} {EPS}} 1}
+    then {AGM {BN./ {BN.+ :a :g} 2}
+              {BN.sqrt {BN.* :a :g}}}
+    else :a }}}
+-> AGM
+
+{AGM 1 {BN./ 1 {BN.sqrt 2}}}
+-> 0.8472130847939790866064991234821916364814459103269421850605793726597339