Re: mathematical discrepancies

Check http://php.net/manual/en/language.types.float.php Quote: Warning Floating point precision It is typical that simple decimal fractions like 0.1 or 0.7 cannot be converted into their internal binary counterparts without a small loss of precision. This can lead to confusing results: for example, floor((0.1+0.7)*10) will usually return 7 instead of the expected 8, since the internal representation will be something like 7.9. This is due to the fact that it is impossible to express some fractions in decimal notation with a finite number of digits. For instance, 1/3 in decimal form becomes 0.3. So never trust floating number results to the last digit, and never compare floating point numbers for equality. If higher precision is necessary, the arbitrary precision math functions and gmp functions are available. On Thu, Aug 14, 2008 at 2:55 PM, Andrew Martin <sublimino@gmail.com> wrote: > Hello, > > Can anybody shed any light on this behaviour please? > > PHP Version 5.2.5 on XP > > > $a = 1754.00 ; > $b = 1754.03 ; > $diff = abs($b) - abs($a); > > echo "$diff<br/>"; //output: 0.03 > > $a = 1754.00 ; > $b = 1754.09 ; > $diff = abs($b) - abs($a); > > echo "$diff<br/>"; //output :0.0899999999999 > > $a = 1754.01 ; > $b = 1754.02 ; > $diff = abs($b) - abs($a); > > echo $diff; //output: 0.00999999999999 > > > Is this expected behaviour? Can anybody reproduce this? > > Many thanks, > > > Andy > > -- > PHP Database Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > >