// (c) Andreas Meier
// Sophie-Scholl-Realschule Weiden
// erstellt am 31.12. 2003

function start()
{
document.Parameter.ax.value =3;
document.Parameter.ay.value =7;
document.Parameter.bx.value =7;
document.Parameter.by.value =-2;
document.Parameter.gleichung.value ="y = -2,25x + 13,75";
}

function reset()
{
document.Parameter.ax.value ="";
document.Parameter.ay.value ="";
document.Parameter.bx.value ="";
document.Parameter.by.value ="";
document.Parameter.gleichung.value ="";
}

function geraglei()
{
if (document.Parameter.ax.value!="")
{
var dummy = eval(document.Parameter.ax.value.replace(",","."));
xa = dummy;
}
else
{
xa=0;
}
if (document.Parameter.ay.value!="")
{
var dummy = eval(document.Parameter.ay.value.replace(",","."));
ya = dummy;
}
else
{
ya=0;
}
if (document.Parameter.bx.value!="")
{
var dummy = eval(document.Parameter.bx.value.replace(",","."));
xb = dummy;
}
else
{
xb=0;
}
if (document.Parameter.by.value!="")
{
var dummy = eval(document.Parameter.by.value.replace(",","."));
yb = dummy;
}
else
{
yb=0;
}

if (xa!=xb)
{
m = (ya-yb)/(xa-xb);
m = Math.round(m*100+0.49)/100;
t = ya-m*xa
t = Math.round(t*100+0,49)/100;
if (m == 1) var m ="";
if (m==-1) var m ="-"
if (t==0)var rterm = "y = "+m+"x";
if (t<0)var rterm = "y = "+m+"x "+t;
if (t>0)var rterm = "y = "+m+"x +"+t;

}
else
{
var rterm = "x = "+xa;
}

if (yb == ya) var rterm = "y = "+ya;
if (xa==xb && ya==yb)var rterm = "Zwei identische Punkte";
if (xa==0 && xb==0 && ya==0 && yb==0) var rterm = "Fehlende Punkteingabe";
for (i = 1; i<3 ; i++) {
var rterm = String(rterm).replace(".",",");
}

document.Parameter.gleichung.value = rterm
}