Initial data commit

Task/Pi/C-sharp/pi-2.cs

@@ -0,0 +1,71 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Numerics;
+
+namespace EnumeratePi {
+  class Program {
+    private const int N = 60;
+    private const string ZS = " +-";
+    static void Main() {
+      Console.WriteLine("Digits of PI");
+      Console.WriteLine(new string('=', N + 13));
+
+      Console.WriteLine("Decimal    : {0}", string.Concat(PiDigits(10).Take(N).Select(_ => _.ToString("d"))));
+      Console.WriteLine("Binary     : {0}", string.Concat(PiDigits(2).Take(N).Select(_ => _.ToString("d"))));
+      Console.WriteLine("Quaternary : {0}", string.Concat(PiDigits(4).Take(N).Select(_ => _.ToString("d"))));
+      Console.WriteLine("Octal      : {0}", string.Concat(PiDigits(8).Take(N).Select(_ => _.ToString("d"))));
+      Console.WriteLine("Hexadecimal: {0}", string.Concat(PiDigits(16).Take(N).Select(_ => _.ToString("x"))));
+      Console.WriteLine("Alphabetic : {0}", string.Concat(PiDigits(26).Take(N).Select(_ => (char) ('A' + _))));
+      Console.WriteLine("Fun        : {0}", string.Concat(PiDigits(ZS.Length).Take(N).Select(_ => ZS[(int)_])));
+
+      Console.WriteLine("Nibbles    : {0}", string.Concat(PiDigits(0x10).Take(N/2).Select(_ => string.Format("{0:x1} ", _))));
+      Console.WriteLine("Bytes      : {0}", string.Concat(PiDigits(0x100).Take(N/3).Select(_ => string.Format("{0:x2} ", _))));
+      Console.WriteLine("Words      : {0}", string.Concat(PiDigits(0x10000).Take(N/5).Select(_ => string.Format("{0:x4} ", _))));
+      Console.WriteLine("Dwords     : {0}", string.Concat(PiDigits(0x100000000).Take(N/9).Select(_ => string.Format("{0:x8} ", _))));
+
+      Console.WriteLine(new string('=', N + 13));
+      Console.WriteLine("* press any key to exit *");
+      Console.ReadKey();
+    }
+
+    /// <summary>Enumerates the digits of PI.</summary>
+    /// <param name="b">Base of the Numeral System to use for the resulting digits (default = Base.Decimal (10)).</param>
+    /// <returns>The digits of PI.</returns>
+    static IEnumerable<long> PiDigits(long b = 10) {
+      BigInteger
+        k = 1,
+        l = 3,
+        n = 3,
+        q = 1,
+        r = 0,
+        t = 1
+        ;
+
+      // skip integer part
+      var nr = b * (r - t * n);
+      n = b * (3 * q + r) / t - b * n;
+      q *= b;
+      r = nr;
+
+      for (; ; ) {
+        var tn = t * n;
+        if (4 * q + r - t < tn) {
+          yield return (long)n;
+          nr = b * (r - tn);
+          n = b * (3 * q + r) / t - b * n;
+          q *= b;
+        } else {
+          t *= l;
+          nr = (2 * q + r) * l;
+          var nn = (q * (7 * k) + 2 + r * l) / t;
+          q *= k;
+          l += 2;
+          ++k;
+          n = nn;
+        }
+        r = nr;
+      }
+    }
+  }
+}