{ > Src.RealFn } program real_functions (output);

const pi = 3.14159265;
      ysz = 512; ysc = 496.0;
      xsz = 640; xsc = 640.0; xszdpix = 80;
      pix = 8;

var i : integer;

procedure Axes;
begin
  mode (1);
  vdu (29, xsz MOD 256, xsz DIV 256, ysz MOD 256, ysz DIV 256);
  plot (4, 0, -ysz); plot (5, 0, ysz);
  plot (4, -xsz, 0); plot (5, xsz, 0)
end;

begin
  axes;

{ Sin plot }
  vdu (18, 0, 1, 17, 1); writeln ('Sin');
  plot (4, -xsz, round (ysc * sin (-pi)));
  for i := -xszdpix+1 to xszdpix do
    plot (5, pix*i, round (ysc * sin (pix*i*pi/xsc)));

{ Cos plot }
  vdu (18, 0, 2, 17, 2); writeln ('Cos');
  plot (4, -xsz, round (ysc * cos (-pi)));
  for i := -xszdpix+1 to xszdpix do
    plot (5, pix*i, round (ysc * cos (pix*i*pi/xsc)));

{ Arctan plot }
  vdu (18, 0, 3, 17, 3); writeln ('Arctan');
  plot (4, -xsz, round (ysc * arctan (-pi)) DIV 2);
  for i := -xszdpix+1 to xszdpix do
    plot (5, pix*i, round (ysc * arctan (pix*i*pi/xsc)) DIV 2);

  writeln ('Press Shift');
  repeat until inkey (-1) = -1;

  axes;

{ Ln plot }
  vdu (18, 0, 1, 17, 1); writeln ('Ln');
  plot (4, pix, round (ysc * ln (pix*2.0/xsc)));
  for i := 2 to xszdpix do
    plot (5, pix*i, round (ysc * ln (pix*i*2.0/xsc)));

{ Sqrt plot }
  vdu (18, 0, 2, 17, 2); writeln ('Sqrt');
  plot (4, pix, 0);
  for i := 1 to xszdpix do
     plot (5, pix*i, round (ysc * sqrt (pix*i/xsc)));
  plot (4, pix, 0);
  for i := 1 to xszdpix do
     plot (5, pix*i, -round (ysc * sqrt (pix*i/xsc)));

{ Sqr plot }
  vdu (18, 0, 3, 17, 3); writeln ('Sqr');
  plot (4, -xsz, round (ysc));
  for i := -xszdpix+1 to xszdpix do        
    plot (5, pix*i, round (ysc * sqr (pix*i/xsc)));
end.