Data commit

Task/Pi/Pascal/pi.pas

@@ -0,0 +1,64 @@
+Program Pi_Spigot;
+const
+  n   = 1000;
+  len = 10*n div 3;
+
+var
+  j, k, q, nines, predigit: integer;
+  a: array[0..len] of longint;
+
+function OneLoop(i:integer):integer;
+var
+  x: integer;
+begin
+  {Only calculate as far as needed }
+  {+16 for security digits ~5 decimals}
+  i := i*10 div 3+16;
+  IF i > len then
+    i := len;
+  result := 0;
+  repeat   {Work backwards}
+    x  := 10*a[i] + result*i;
+    result := x div (2*i - 1);
+    a[i]   := x - result*(2*i - 1);//x mod (2*i - 1)
+    dec(i);
+  until i<= 0 ;
+end;
+
+begin
+
+  for j := 1 to len do
+    a[j] := 2;                 {Start with 2s}
+  nines := 0;
+  predigit := 0;               {First predigit is a 0}
+
+  for j := 1 to n do
+  begin
+    q := OneLoop(n-j);
+    a[1] := q mod 10;
+    q := q div 10;
+    if q = 9 then
+      nines := nines + 1
+    else
+      if q = 10 then
+      begin
+        write(predigit+1);
+        for k := 1 to nines do
+          write(0);            {zeros}
+        predigit := 0;
+        nines := 0
+      end
+      else
+      begin
+        write(predigit);
+        predigit := q;
+        if nines <> 0 then
+        begin
+          for k := 1 to nines do
+            write(9);
+          nines := 0
+        end
+      end
+  end;
+  writeln(predigit);
+end.