Rounding problem

[laredotornado@zipmail.com]

Hi,

I'm using PHP 4.4.4. I'm confused about the function "round". I have

<?= "prov tax: $provincial_tax " . round($provinci al_tax, 2) . "<BR>
\n" ?>

When $provincial_tax = 7.185, the output above is

prov tax: 7.185 7.18

Shouldn't the second number be 7.19 since 7.185 rounds to 7.19? I
appreciate any insights you may have, - Dave

[PaulB]

Re: Rounding problem

laredotornado@z ipmail.com wrote:

Hi,
>
I'm using PHP 4.4.4. I'm confused about the function "round". I have
>
<?= "prov tax: $provincial_tax " . round($provinci al_tax, 2) . "<BR>
\n" ?>
>
When $provincial_tax = 7.185, the output above is
>
prov tax: 7.185 7.18
>
Shouldn't the second number be 7.19 since 7.185 rounds to 7.19? I
appreciate any insights you may have, - Dave

<?php
$provincial_tax = 7.185;
$provtax = round($provinci al_tax, 2);
echo $provtax;
?>

I ran that in DzSoft PHP Editor 4.1.2. and it gave me 7.19, then I ran it on
my server running PHP version 5.2.5 and it gave 7.19 so what's the problem?
Maybe it's the PHP version.

Paul
--
Add an underscore after the p to reply

[Jerry Stuckle]

Re: Rounding problem

laredotornado@z ipmail.com wrote:

Hi,
>
I'm using PHP 4.4.4. I'm confused about the function "round". I have
>
<?= "prov tax: $provincial_tax " . round($provinci al_tax, 2) . "<BR>
\n" ?>
>
When $provincial_tax = 7.185, the output above is
>
prov tax: 7.185 7.18
>
Shouldn't the second number be 7.19 since 7.185 rounds to 7.19? I
appreciate any insights you may have, - Dave

This has been discussed many times in this forum, and it has to do with
the internal representation of floating point numbers in the hardware.
7.185 is a repeating decimal (like 1/3 is in decimal) and cannot be
represented exactly.

The value is probably not 7.185, but something like 7.184999999345.
Printed, it shows 7.185. But rounding will take it to 7.184, which is
correct. If you want to round to 7.185, you have to add a fudge factor,
i.e.
round($provinci al_tax + 0.0001);

Or do everything using integers and only change it when you go to display.



--
=============== ===
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attgl obal.net
=============== ===

[The Natural Philosopher]

Re: Rounding problem

laredotornado@z ipmail.com wrote:

Hi,
>
I'm using PHP 4.4.4. I'm confused about the function "round". I have
>
<?= "prov tax: $provincial_tax " . round($provinci al_tax, 2) . "<BR>
\n" ?>
>
When $provincial_tax = 7.185, the output above is
>
prov tax: 7.185 7.18
>
Shouldn't the second number be 7.19 since 7.185 rounds to 7.19? I
appreciate any insights you may have, - Dave

7.185 does not 'round' either way..its a 50-50 choice to round it up or
down.