Data commit

Task/Arithmetic-geometric-mean/Visual-Basic-.NET/arithmetic-geometric-mean-1.vb

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+Imports System.Math
+Imports System.Console
+
+Module Module1
+
+    Function CalcAGM(ByVal a As Double, ByVal b As Double) As Double
+        Dim c As Double, d As Double = 0, ld As Double = 1
+        While ld <> d : c = a : a = (a + b) / 2 : b = Sqrt(c * b)
+            ld = d : d = a - b : End While : Return b
+    End Function
+
+    Function DecSqRoot(ByVal v As Decimal) As Decimal
+        Dim r As Decimal = CDec(Sqrt(CDbl(v))), t As Decimal = 0, d As Decimal = 0, ld As Decimal = 1
+        While ld <> d : t = v / r : r = (r + t) / 2
+            ld = d : d = t - r : End While : Return t
+    End Function
+
+    Function CalcAGM(ByVal a As Decimal, ByVal b As Decimal) As Decimal
+        Dim c As Decimal, d As Decimal = 0, ld As Decimal = 1
+        While ld <> d : c = a : a = (a + b) / 2 : b = DecSqRoot(c * b)
+            ld = d : d = a - b : End While : Return b
+    End Function
+
+    Sub Main(ByVal args As String())
+        WriteLine("Double  result: {0}", CalcAGM(1.0, DecSqRoot(0.5)))
+        WriteLine("Decimal result: {0}", CalcAGM(1D, DecSqRoot(0.5D)))
+        If System.Diagnostics.Debugger.IsAttached Then ReadKey()
+    End Sub
+
+End Module

Task/Arithmetic-geometric-mean/Visual-Basic-.NET/arithmetic-geometric-mean-2.vb

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+Imports System.Math
+Imports System.Console
+Imports BI = System.Numerics.BigInteger
+
+Module Module1
+
+    Function BIP(ByVal leadDig As Char, ByVal numDigs As Integer) As BI
+        BIP = BI.Parse(leadDig & New String("0"c, numDigs))
+    End Function
+
+    Function IntSqRoot(ByVal v As BI, ByVal res As BI) As BI ' res is the initial guess of the square root
+        Dim d As BI = 0, dl As BI = 1
+        While dl <> d :  IntSqRoot = v / res : res = (res + IntSqRoot) / 2
+            dl = d : d = IntSqRoot - res : End While
+    End Function
+
+    Function CalcByAGM(ByVal digits As Integer) As BI
+        Dim a As BI = BIP("1"c, digits), ' value is 1, extended to required number of digits
+            c as BI, ' a temporary variable for swapping a and b
+            diff As BI = 0, ldiff As BI = 1 ' difference of a and b, last difference
+        CalcByAGM = BI.Parse(String.Format("{0:0.00000000000000000}", ' initial value of square root of 0.5
+            Sqrt(0.5)).Substring(2) & New String("0"c, digits - 17))
+        CalcByAGM = IntSqRoot(BIP("5"c, (digits << 1) - 1), CalcByAGM) ' value is now the square root of 0.5
+        While ldiff <> diff : c = a : a = (a + CalcByAGM) >> 1 : CalcByAGM = IntSqRoot(c * CalcByAGM, a)
+            ldiff = diff : diff = a - CalcByAGM : End While
+    End Function
+
+    Sub Main(ByVal args As String())
+        Dim digits As Integer = 25000
+        If args.Length > 0 Then Integer.TryParse(args(0), digits) : _
+            If digits < 1 OrElse digits > 999999 Then digits = 25000
+        WriteLine("0.{0}", CalcByAGM(digits))
+        If System.Diagnostics.Debugger.IsAttached Then ReadKey()
+    End Sub
+
+End Module