How to prevent division by zero in PHP?

[soerenfleischer]

Is there a way to prevent a division by 0 in PHP?

I'm making a graph-drawer, which crashes if a function has pole-points, because those cause divisions by zero...

I'm afraid the functions is_infinite() and is_finite() are not available in the "normal" version of PHP...


Any ideas?
Thanks in advance!

 

[ShockingAlberto]

What's wrong with a simple if statement?
if($x>0){
$x=$x/$y
}

 

[soerenfleischer]

The problem is, the graph-drawer should accept user-entered functions. And functions can have more than just one factor under the fraction line and can contain many other factors, so the problem can't be solved like that...


BTW, you mean
if($y>0){
$x=$x/$y
}
right?

 

[Teaser]

Well surely you need to write a function which calculates what values will give you the demoninator equal to zero, i.e equate the denominator to 0 and solve. The values for $x (or whatever the variable is - assuming theres only one) you get from this will be those which make the denomiator zero.

When drawing the graph make sure you aren't using of these values.

Not a 10 minute job, but it would work.