Dehnbares u. beschriftetes Koordinatensystem

cLoWn

Grünschnabel
Hi Folx,
ich brauche ganz dringend eure Hilfe!
Ich versuche ein dehnbares und beschriftetes Koordinatensystem
in pascal zu erstellen, komme aber leider nicht weiter.
Bitte helft mir!

cLoWn

PROGRAM pqform;
USES crt, graph;
VAR
a, b, c, x, x1, x2, d, y, g :real;
li, re, zx, zy, bildx, bildy, i :integer;

PROCEDURE init_g;
var
g0, g1 :integer;
begin
g0 := detect;
initgraph(g0, g1, 'BGI')
END;

PROCEDURE plott;
BEGIN
line(320,1,320,480);
line(1,240,640,240);
zx := 320;
zy := 240;
moveto(zx+li*50, round(zy-10*li*li+b*li+c));
li := li*100;
re := re*100;
setcolor(red);
FOR i := li TO re DO
BEGIN
x := i/100;
y := a*x*x+b*x+c;
bildx := round(zx+x*50);
bildy := round(zy-y*10);
lineto(round(bildx), round(bildy));
END;
END;

BEGIN
clrscr;
writeln('a:'); readln(a);
writeln('b:'); readln(b);
writeln('c:'); readln(c);
writeln('Untersuchungsbereich:'); readln(li); readln(re);
IF a = 0
THEN
IF b <> 0
THEN BEGIN
x := -(c/b);
writeln('x= ', x)
END
ELSE
IF c <> 0
THEN writeln('|L = { }')
ELSE BEGIN
writeln('|L = |R');
writeln('x= ', x);
END
ELSE
d := (b*b)/(4*a*a) -(c/a);
IF d > 0
THEN BEGIN
x1 := -(b/2) + sqrt(d);
x2 := -(b/2) - sqrt(d);
writeln('x1= ', x1);
writeln('x2= ', x2);
END
ELSE
IF d = 0
THEN
BEGIN
x := -b/2;
writeln('x = ', x);
END
ELSE
writeln('|L = { }');
readln;
init_g;
plott;
readln;
closegraph;
readln;

END.