Re: Using Equal with Real Numbers

*To*: mathgroup at smc.vnet.net*Subject*: [mg123188] Re: Using Equal with Real Numbers*From*: Alan <alan.isaac at gmail.com>*Date*: Fri, 25 Nov 2011 04:59:13 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <jalb8i$s6h$1@smc.vnet.net>

On Nov 24, 6:53 am, Gabriel Landi <gtla... at gmail.com> wrote: > (This actually depends on the OS and perhaps other things). The point is > that he recognizes 0.6 as a member of list1 but not 0.7, even though > both have the same InputForms. Can you please explain this in more detail? I assume this turn on the fact that "MemberQ tests for structural matches, not numerical equality", but how can I see the structural mismatch? Why does it only apply to 0.7? I.e., lst1 = {0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0}; lst2 = Range[0, 1, 0.1]; Map[MemberQ[lst2, #] &, lst1] => {True, True, True, True, True, True, True, False, True, True, True} Thanks, Alan Isaac