note 75124 added to language.types.float

>>rune at zedeler dot dk >>05-Mar-2007 06:44 >>Comparing infinite values gives REALLY STRANGE results. >>INF<INF is true >>INF>INF is true >>INF==INF is false >>INF===INF is true >>So if someone tells you that $a==$b implies $a===$b then you can tell them no, $a=$b=INF is >>a counterexample. :-/ The above is incorrect. You have to remember, that INF is not a discrete value, it is more or less a flag indicating a state: "Infinity" does not necessarily mean that the result is actually infinite. It simply means "too large to represent"(From Wikipedia). Moreover, INF cannot ever be equal to INF, as the following example shows: (+INF) + (+7) = (+INF) For INF==INF to be true, (INF + 7)==INF would also have to be true due to the above; it is not, again, because INF is not a value, it is a state. Furthermore, logically, $a=$b=INF is not a counterexample; it would be if INF==INF was true but INF===INF was false(or if you had said $a===$b implies $a==$b), but this is not the case, as implication is not a two-way street. Following is a truth table for p => q: p q p=>q F F T F T T T F F T T T So we have: INF==INF (implies) INF===INF False (implies) True True (from the truth table above) thus, $a=$b=INF is not a counterexample, since the system remains logically consistant. ---- Server IP: 66.207.199.35 Probable Submitter: 68.151.136.226 ---- Manual Page -- http://www.php.net/manual/en/language.types.float.php Edit -- https://master.php.net/note/edit/75124 Del: integrated -- https://master.php.net/note/delete/75124/integrated Del: useless -- https://master.php.net/note/delete/75124/useless Del: bad code -- https://master.php.net/note/delete/75124/bad+code Del: spam -- https://master.php.net/note/delete/75124/spam Del: non-english -- https://master.php.net/note/delete/75124/non-english Del: in docs -- https://master.php.net/note/delete/75124/in+docs Del: other reasons-- https://master.php.net/note/delete/75124 Reject -- https://master.php.net/note/reject/75124 Search -- https://master.php.net/manage/user-notes.php