函数<SCRIPT LANGUAGE="JavaScript">
<!-- Begin
var a, b, c;
function xtop(form) {
form.u.value = (form.b.value * -1) / (form.a.value * 2);
}
function ytop(form) {
form.u2.value = -1 * (form.b.value * form.b.value) / (4 * form.a.value) - (-1 * form.c.value);
}
function doCoord(form) {
form.co.value = form.u.value + "," + form.u2.value;
}
function disc(form) {
form.o.value = (form.b.value * form.b.value) - (form.a.value * form.c.value * 4);
}
function zeroes1(form) {
form.n.value = ((form.b.value * -1) - (Math.sqrt(form.o.value))) / (form.a.value * 2);
}
function zeroes2(form) {
form.n2.value = ((form.b.value * -1) - (-1 * Math.sqrt(form.o.value))) / (form.a.value * 2);
}
function move_in(img_name,img_src) {
document[img_name].src=img_src;
}
//  End -->
</script>
<form>
<table bgcolor="#C0C0C0" cellspacing=2 cellpadding=2 border=3>
<tr>
<td>
<b>
<h3>Parabolic Calculator</h3>
<input name="a" size="3">X²+
<input name="b" size="3">X +
<input name="c" size="3">


<input type="button" value="x-top" name="x-top" onclick="xtop(this.form)">
<input type="button" value="y-top" name="y-top" onclick="ytop(this.form)">
<input type="button" value="crd" name="crd" onclick="doCoord(this.form)">
<input type="button" value="disc." name="D" onclick="disc(this.form)">


<input type="button" value="0-points" name="zeroes" onclick="zeroes1(this.form);zeroes2(this.form)">
<input type="button" onclick="xtop(this.form);ytop(this.form);doCoord(this.form);disc(this.form);zeroes1(this.form);zeroes2(this.form)" value="do all">
<input type="button" name="pics" value="show e.g." onClick="if(form.a.value>0 && form.o.value>0)move_in('p','p2.gif');if (form.a.value<0 && form.o.value>0)move_in('p','p3.gif'); if(form.a.value>0 && form.o.value==0) move_in('p','p4.gif'); if(form.a.value<0 && form.o.value==0) move_in('p','p5.gif'); if(form.a.value>0 && form.o.value<0) move_in('p','p6.gif'); if(form.a.value<0 && form.o.value<0) move_in('p','p7.gif')" value="show e.g.">


<input type="text" name="u" size="8"> x-top

<input type="text" name="u2" size="8"> y-top

<input type="text" size="8" name="co" onmouseover="form.rem.value=form.co.value"> Coord.

<input type="text" size="8" name="o"> Discriminant

<input type="text" size="8" name="n"> neg zero pt.

<input type="text" size="8" name="n2"> pos zero pt.
<input type="hidden" value="" name="rem">

<input type="reset" value="reset">

</b>
</td>
<td><img src=http://www.163design.net/a/q/"p1.gif" width=200 name="p" height=200 border=0 alt=""></td>
</tr>
</table>
</form>