ID: 41907
User updated by: milman at gmx dot de
Reported By: milman at gmx dot de
Status: Bogus
Bug Type: *Math Functions
Operating System: windows xp
PHP Version: 5.2.3
New Comment:
#ifndef PHP_ROUND_FUZZ
# ifndef PHP_WIN32
# define PHP_ROUND_FUZZ 0.50000000001
# else
# define PHP_ROUND_FUZZ 0.5
# endif
#endif
#define PHP_ROUND_WITH_FUZZ(val, places) { \
double tmp_val=val, f = pow(10.0, (double) places); \
tmp_val *= f; \
if (tmp_val >= 0.0) { \
tmp_val = floor(tmp_val + PHP_ROUND_FUZZ); \
} else { \
tmp_val = ceil(tmp_val - PHP_ROUND_FUZZ); \
} \
tmp_val /= f; \
val = !zend_isnan(tmp_val) ? tmp_val : val; \
} \
why for windows not 0.50000000001?
i think that would solve the problem.
Previous Comments:
------------------------------------------------------------------------
[2007-07-05 19:00:14] milman at gmx dot de
ok,
but that is the same for other numbers too.
function tround ($r0)
{
$rr0 = round ($r0,2) ;
$str1 = sprintf ("%015.20f", $r0) ;
echo "$r0 : $rr0 $str1<br>\n" ;
}
tround (8.055,2) ;
tround (8.155,2) ;
tround (8.255,2) ;
8.055 : 8.06 8.05499999999999971578
8.155 : 8.15 8.15499999999999936051
8.255 : 8.26 8.25500000000000078160
so i don't understand it.
for me it is a bug.
------------------------------------------------------------------------
[2007-07-05 18:50:48] [EMAIL PROTECTED]
php -r 'echo sprintf("%15.20f", 8.155);'
8.15499999999999936051
------------------------------------------------------------------------
[2007-07-05 18:48:25] milman at gmx dot de
sorry but i can't accept this answer.
for me it seem like, round-problem than bogus and standard answer.
php use common round (Symmetric Arithmetic Rounding)
Decide which is the last digit to keep.
Increase it by 1 if the next digit is 5 or more (this is called
rounding up)
Leave it the same if the next digit is 4 or less (this is called
rounding down)
and then round (8.155, 2) is 8.16 and not 8.15
sprintf ("%15.8f", 8.155) is 000008.15500000
so it is not a problem from intern representation.
the rounding problem occurs at number_format and sprintf too.
round
------------------------------------------------------------------------
[2007-07-05 16:30:05] [EMAIL PROTECTED]
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:
http://docs.sun.com/source/806-3568/ncg_goldberg.html
Thank you for your interest in PHP.
.
------------------------------------------------------------------------
[2007-07-05 16:27:24] milman at gmx dot de
Description:
------------
wrong result from round(64.365,2)
should be 64.37 not 64.36
Reproduce code:
---------------
<?
echo "right: round (63.365,2) = " . round (63.365,2) . "<br>\n" ;
echo "wrong: round (64.365,2) = " . round (64.365,2) . "<br>\n" ;
echo "wrong: round (81.365,2) = " . round (81.365,2) . "<br>\n" ;
echo "right: round (82.365,2) = " . round (82.365,2) . "<br>\n" ;
?>
Expected result:
----------------
allway .37 not somtimes .36
------------------------------------------------------------------------
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Edit this bug report at http://bugs.php.net/?id=41907&edit=1
