Reducing the $a to say $a=0.05 would flatten the curve. and the x-?? seems to level the top and bottom
The formula is a threwback to my school maths in the 60's so I,m not too sure what the rest of it does.
You can get a graphical representation at
this site or google "parabola" if that one doesn't load.
<?php
$text= array ("this","is","a","routine","to","create","curve d", "text","just","change","the","variables","with","f ifteen","words");
for ($x=0;$x<15;$x++) {
?>
<span style="margin-left:<?php echo curvey($x);?> em"><?php echo $text[$x] ?></span><br>
<?php }
function curvey ($x)
{
$inset=10;
$a=.05;
$b=1;
$c=1;
$y= $a*($x-17)*($x-17)+$b*($x-17)+$c;
$y=$inset-$y;
return $y;
}
?>
As the $b+$c are both set to 1 I guess leaving them out won't make much difference. Perhaps a mathemetican could create a general formula based just on the array count
bob