so you can combine your original test with a test for infinities ((= <.) *. -.@(e.&_ __)) ] 2.1 1 __ 0 1
0 1 0 1 1 On Sunday, August 2, 2020, 08:24:54 a.m. EDT, Skip Cave <s...@caveconsulting.com> wrote: What I'm really looking for, is a verb that finds integers in a list: datatype 2.5 floating datatype 3 integer datatype __ floating So J considers __ as "floating" So I want a verb "isinteger" that marks the integers in a vector, where __ is in the list, and is considered floating: isinteger 1 2.5 __ 3 4.5 6 1 0 0 1 0 1 And maybe the inverse also: isfloating 1 2.5 __ 3 4.5 6 0 1 1 0 1 0 My (=<,) doesn't do it: (=<.)1 2.5 __ 3 4.5 6 1 0 1 1 0 1 So what would "isinteger" look like? Skip Skip Cave Cave Consulting LLC On Sun, Aug 2, 2020 at 1:44 AM Skip Cave <s...@caveconsulting.com> wrote: > I use the (=<.) verb to find integers in a list: > > > * (=<.)1 2.5 2.7 3 4.5 6* > > *1 0 0 1 0 1* > > * (#~(=<.))1 2.5 2.7 3 4.5 6* > > *1 3 6* > > I ran across an interesting result when infinity is in the list: > > * (=<.)1 2.5 __ 3 4.5 6* > > *1 0 1 1 0 1* > > * (#~(=<.))1 2.5 __ 3 4.5 6* > > *1 __ 3 6* > > > So J is saying that the floor of infinity is infinity (and the ceiling of > infinity is also infinity). Since infinity is not a number, it would seem > that an error should be generated when taking the floor of infinity, or > perhaps NAN, or a zero? In any case, this messes up my nice integer-finding > verb. Is the\re a mathematical justification for defining the floor of > infinity to be infinity? > https://math.stackexchange.com/questions/981708/limit-of-floor-function-when-x-goes-infinity > > > Skip > > > Skip Cave > Cave Consulting LLC > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
