#40622 [NEW]: round function

[bruno dot boccara at d2b dot com]

From: bruno dot boccara at d2b dot com
Operating system: windows 2003 Apache 2
PHP version: 4.4.5
PHP Bug Type: Math related
Bug description: round function

Description:
------------
round function gives wrong value.

Please do not send me to
[url]http://docs.sun.com/source/806-3568/ncg_goldberg.html[/url], you have to admit
that this is a bug !!!!!
if not, php CANNOT be use in production site with mathematical functions
!!!

Reproduce code:
---------------
<?
// 140.25*(1-(34/100)) = 92.565


echo "formula = ". round(((140.25*(1-(34/100)))),2);echo "<br>";

echo "direct = ".round (92.565, 2);echo "<br>";

$valeur = 140.25*(1-(34/100));

echo "value = ".round($valeur,2);echo "<br>";

settype($valeur,"string");
settype($valeur,"float");

echo "value2 = ".round($valeur,2);

?>

Expected result:
----------------
formula = 92.57
direct = 92.57
value = 92.57
value2 = 92.57

Actual result:
--------------
formula = 92.56 // WRONG !
direct = 92.57
value = 92.56 // WRONG !
value2 = 92.57

--
Edit bug report at [url]http://bugs.php.net/?id=40622&edit=1[/url]
--
Try a CVS snapshot (PHP 4.4): [url]http://bugs.php.net/fix.php?id=40622&r=trysnapshot44[/url]
Try a CVS snapshot (PHP 5.2): [url]http://bugs.php.net/fix.php?id=40622&r=trysnapshot52[/url]
Try a CVS snapshot (PHP 6.0): [url]http://bugs.php.net/fix.php?id=40622&r=trysnapshot60[/url]
Fixed in CVS: [url]http://bugs.php.net/fix.php?id=40622&r=fixedcvs[/url]
Fixed in release: [url]http://bugs.php.net/fix.php?id=40622&r=alreadyfixed[/url]
Need backtrace: [url]http://bugs.php.net/fix.php?id=40622&r=needtrace[/url]
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Try newer version: [url]http://bugs.php.net/fix.php?id=40622&r=oldversion[/url]
Not developer issue: [url]http://bugs.php.net/fix.php?id=40622&r=support[/url]
Expected behavior: [url]http://bugs.php.net/fix.php?id=40622&r=notwrong[/url]
Not enough info: [url]http://bugs.php.net/fix.php?id=40622&r=notenoughinfo[/url]
Submitted twice: [url]http://bugs.php.net/fix.php?id=40622&r=submittedtwice[/url]
register_globals: [url]http://bugs.php.net/fix.php?id=40622&r=globals[/url]
PHP 3 support discontinued: [url]http://bugs.php.net/fix.php?id=40622&r=php3[/url]
Daylight Savings: [url]http://bugs.php.net/fix.php?id=40622&r=dst[/url]
IIS Stability: [url]http://bugs.php.net/fix.php?id=40622&r=isapi[/url]
Install GNU Sed: [url]http://bugs.php.net/fix.php?id=40622&r=gnused[/url]
Floating point limitations: [url]http://bugs.php.net/fix.php?id=40622&r=float[/url]
No Zend Extensions: [url]http://bugs.php.net/fix.php?id=40622&r=nozend[/url]
MySQL Configuration Error: [url]http://bugs.php.net/fix.php?id=40622&r=mysqlcfg[/url]

[johannes@php.net]

ID: 40622
Updated by: [email]johannes@php.net[/email]
Reported By: bruno dot boccara at d2b dot com
-Status: Open
+Status: Bogus
Bug Type: Math related
Operating System: windows 2003 Apache 2
PHP Version: 4.4.5
New Comment:

Floating point values have a limited precision. Hence a value might
not have the same string representation after any processing. That also
includes writing a floating point value in your script and directly
printing it without any mathematical operations.

If you would like to know more about "floats" and what IEEE
754 is read this:
[url]http://docs.sun.com/source/806-3568/ncg_goldberg.html[/url]

Thank you for your interest in PHP.

..


Previous Comments:
------------------------------------------------------------------------

[2007-02-24 21:36:47] bruno dot boccara at d2b dot com

Description:
------------
round function gives wrong value.

Please do not send me to
[url]http://docs.sun.com/source/806-3568/ncg_goldberg.html[/url], you have to
admit that this is a bug !!!!!
if not, php CANNOT be use in production site with mathematical
functions !!!

Reproduce code:
---------------
<?
// 140.25*(1-(34/100)) = 92.565


echo "formula = ". round(((140.25*(1-(34/100)))),2);echo "<br>";

echo "direct = ".round (92.565, 2);echo "<br>";

$valeur = 140.25*(1-(34/100));

echo "value = ".round($valeur,2);echo "<br>";

settype($valeur,"string");
settype($valeur,"float");

echo "value2 = ".round($valeur,2);

?>

Expected result:
----------------
formula = 92.57
direct = 92.57
value = 92.57
value2 = 92.57

Actual result:
--------------
formula = 92.56 // WRONG !
direct = 92.57
value = 92.56 // WRONG !
value2 = 92.57


------------------------------------------------------------------------


--
Edit this bug report at [url]http://bugs.php.net/?id=40622&edit=1[/url]

[bruno dot boccara at d2b dot com]

ID: 40622
User updated by: bruno dot boccara at d2b dot com
Reported By: bruno dot boccara at d2b dot com
Status: Bogus
Bug Type: Math related
Operating System: windows 2003 Apache 2
PHP Version: 4.4.5
New Comment:

Did I send an email to a robot ??
Each user who ask this question get the same answer.
You should be ashaimed to do this. You know that this is a a very big
bug of PHP and no one is ready to resolve it !

This is not a way to do.
I'm very very desappointed.

For other users with this problem, you can do like me in the example to
avoid this problem. This will slow down a little the result. Use the
settype function to convert the number to string and then to float. I
did'n test it in all cases, but it seems to work.


Previous Comments:
------------------------------------------------------------------------

[2007-02-24 22:05:52] [email]johannes@php.net[/email]

Floating point values have a limited precision. Hence a value might
not have the same string representation after any processing. That also
includes writing a floating point value in your script and directly
printing it without any mathematical operations.

If you would like to know more about "floats" and what IEEE
754 is read this:
[url]http://docs.sun.com/source/806-3568/ncg_goldberg.html[/url]

Thank you for your interest in PHP.

..

------------------------------------------------------------------------

[2007-02-24 21:36:47] bruno dot boccara at d2b dot com

Description:
------------
round function gives wrong value.

Please do not send me to
[url]http://docs.sun.com/source/806-3568/ncg_goldberg.html[/url], you have to
admit that this is a bug !!!!!
if not, php CANNOT be use in production site with mathematical
functions !!!

Reproduce code:
---------------
<?
// 140.25*(1-(34/100)) = 92.565


echo "formula = ". round(((140.25*(1-(34/100)))),2);echo "<br>";

echo "direct = ".round (92.565, 2);echo "<br>";

$valeur = 140.25*(1-(34/100));

echo "value = ".round($valeur,2);echo "<br>";

settype($valeur,"string");
settype($valeur,"float");

echo "value2 = ".round($valeur,2);

?>

Expected result:
----------------
formula = 92.57
direct = 92.57
value = 92.57
value2 = 92.57

Actual result:
--------------
formula = 92.56 // WRONG !
direct = 92.57
value = 92.56 // WRONG !
value2 = 92.57


------------------------------------------------------------------------


--
Edit this bug report at [url]http://bugs.php.net/?id=40622&edit=1[/url]