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{ The Computer Language Benchmarks Game
http://shootout.alioth.debian.org
contributed by Vincent Snijders
gmp headers by Karl-Michael Schindler
}
{$mode objfpc}
program pidigits_example2;
uses
gmp;
procedure PrintPiDigits(NumDigits: integer);
var
q, r, s, t: MPInteger; // Transformation matrix components.
i, k, digit, c: integer;
line: string[10];
function Extract(x: cardinal): integer;
begin
result := (q * x + r) / (s * x + t);
end;
function IsSafe: boolean;
begin
result := digit = Extract(4);
end;
procedure Produce;
begin
r := 10 * (r - t * digit);
q *= 10;
end;
procedure Consume;
begin
inc(k);
r := r * (2 * k + 1) + q * (4 * k + 2);
t := t * (2 * k + 1) + s * (4 * k + 2);
s *= k;
q *= k;
end;
begin
k := 0;
i := 0;
c := 0;
setlength(line, 10);
q := 1;
r := 0;
s := 0;
t := 1;
while (i < NumDigits) do begin
digit := Extract(3);
while not IsSafe do begin
Consume;
digit := Extract(3);
end;
Produce;
inc(c);
line[c] := chr(ord('0') + digit);
inc(i);
if c = 10 then begin
writeln(line, #9':', i);
c := 0;
end;
end;
if c <> 0 then begin
SetLength(line, c);
writeln(line);
end;
end;
var
n: integer = 27;
begin
if (ParamCount = 1) then
val(ParamStr(1), n);
PrintPiDigits(n);
end.
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