Compute of Pi number

Category: KMP (Club of young programmers)

Author: Ľuboš Saloky
Program: Pi.pas,  Pi2.pas
File exe: Pi.exe,  Pi2.exe

{ pi.pas                                                            }
{ Vypocet cisla Pi.                                                 }
{                                                                   }
{ Author: Ľuboš Saloky                                              }
{ Datum: 01.01.1996                           http://www.trsek.com  }
 
{$G+}
program Vypocet_Cisla_pi;
{ pi=3.14159 26535 89763 23846 26433 83279 50288 41971 }
var x:longint;
    y,t:real;
    ch:char;
    a,b:word;
begin
  writeln(501*65536);
  writeln('1 - Vypocet čísla Piƒ');
  writeln('2 - Test na for longint');
  writeln('3 - Test na for word');
  readln(ch);
  case ch of
    '1':begin
        y:=1;x:=3;
        repeat
          y:=y-1/x;
          Inc(x,2);
          t:=1/x;
          if (x-1) mod 50000=0 then writeln(4*y);
          y:=y+1/x;
          Inc(x,2);
        until t<0.000001;             {pre t<0.000001 cas 31 sekĂşnd}
        writeln(4*y);                 {4*y= 3.14159465}
      end;                            {of case 1}
  '2':begin
        for x:=1 to 20000000 do       {8 sekund pre x longint}
        begin end;
      end;                            {of case 2}
  '3':begin
        for a:=0 to 500 do begin      {11 sekund bez asm nop}
          asm                  {asm zvysuje Ăşcinnost cache,pretoze tieto}
            nop                {dva cykly sa asi navzĂĄjom z cache vyradujĂş}
          end;                 {s asm len 9 sekĂşnd}
          for b:=0 to 65535 do {mimochodom 501*65516=32833536}
            begin end;{pri vypnutej externej cache je cas 9 sekĂşnd bez aj s NOP}
        end;             {po vypnutĂ­ vsetkych kesĂ­ neuveritelnych 49 sekĂşnd}
      end;                     {of case 3}
  end;                         {of case total}
end.
{----------------------------------------------------------------------------}
{             Zaver: medzi kazde dva prikazy vetvenia davaj NOP              }
{----------------------------------------------------------------------------}