Re: [PHP] Math weirdness with doubles...

[D. Wokan]

They are not the same amount.  They each got a different rounding error. 
 Double values only display a small number of decimal places 
(relatively speaking).  If you look at the difference you're getting, 
it's 0.0000000000000142108547152 (I may be off by a zero or two), so 
given you're working with a currency, I'd say you can safely round to 
about 4 or 8 decimal places to get a reasonably accurate result.  I 
typically use 4 since most money types I've seen only go out 4 decimal 
places to begin with.
--
D. Wokan
(Sorry for the double reply, Jon.  Didn't realise this list doesn't set 
the reply-to until it was too late.)

jon roig wrote:

Ok... It's Friday and maybe my brain is dead, but I'm having a weird
problem with some basic math.
Here's a little snippet of the code I'm working with:

---------------------------
echo "<p>Current:$currentAmount:".gettype($currentAmount)." -
Paid:$paidAmount:".gettype($paidAmount)."</p>";
$currentAmount = $currentAmount-$paidAmount;
echo "<p>Final Current: $currentAmount";
-----------------
Straightforward... Yeah?

Here's a sample of the output:
Current:97.6:double - Paid:97.6:double
Final Current: 1.42108547152E-014
Now if both $currentAmount and $paidAmount are doubles, subtracting them
should yield a zero, shouldn't it?
	-- jon

-------------------
jon roig
web developer
email: [EMAIL PROTECTED]
phone: 888.230.7557
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