program FOURIER;
uses crt, modulog, ufastlab;

type tab = array[0..50] of real;

var a,b     : tab;
var i,j,k   : integer;
var s,t     : real;
var epsilon : real;

BEGIN
    for i := 0 to 50 do
        b[i] := 4 / (((2*i+1)*Pi));
    epsilon := 0.01;
    initgraphique;
    fond(white);
    fenetre(-2*Pi,2*Pi,-10,10);
    for j := 1 to 42 do
    begin
        clrscr;
        couleur(blue);
        X_axe(0,0,1);
        Y_axe(0,0,1);
        couleur(red);
        t := -2 * Pi;
        repeat
            s := 0.5;
            i := 0;
            repeat
                s := s + b[i] * sin((2*i+1)*t);
                i := (i + 1);
            until (i >= j); 
            t := t + epsilon;
            point(t,s);
        until (t >= 2 * Pi);
        pausegraphique;
    end;
END.