> 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
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
I see:
(<.= >.) 1 2.5 __ 3 4.5 6
1 0 1 1 0 1
This has the same issue as (=<.)
Skip Cave
On Sun, Aug 2, 2020 at 7:48 AM Skip Cave wrote:
> Henry said:
> <. = >.
>
> I'll try it out:
>
> <. = >. 1 2.5 __ 3 4.5 6
>
> 1 0 0 0 0 0
>
> 0 1 0 1 0 0
>
> 0 0 1 0 0 0
>
> 0 0 0 0 1 0
>
> 0 0 0 0 0
<. = >. doesn't work on infinity, sorry. But you also have trouble
with big finite numbers if you allow tolerant comparison:
(= 0.5&+) 2 ^ 46
1
19j2 ": 0.5 + 2 ^ 46
70368744177664.50
Henry Rich
On 8/2/2020 8:24 AM, Skip Cave wrote:
What I'm really looking for, is a verb that
Henry said:
<. = >.
I'll try it out:
<. = >. 1 2.5 __ 3 4.5 6
1 0 0 0 0 0
0 1 0 1 0 0
0 0 1 0 0 0
0 0 0 0 1 0
0 0 0 0 0 1
Not sure what this does?
Skip
On Sun, Aug 2, 2020 at 7:30 AM Henry Rich wrote:
> <. = >.
>
> Henry Rich
>
> On 8/2/2020 8:24 AM, Skip Cave wrote:
> > What I'm
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
wrote:
What I'm really looking for, is a verb that finds integers in a list:
datatype 2.5
floating
datatype
<. = >.
Henry Rich
On 8/2/2020 8:24 AM, Skip Cave 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
my finiteinteger verb
(quote:
finiteinteger =: ((= <.) *. (~: <:))
keepfinint =: (#~ finiteinteger)
endquote)
does what you want in your simple case
but still, big floats may be troublesome,
just as Henry pointed out
Am 02.08.20 um 15:00 schrieb Skip Cave:
I see:
(<.= >.) 1 2.5 __ 3 4.5 6
The floor of infinity being infinity is not the real problem, opinion.
Or at least not the only problem. And, integer infinity is not a
particularly new concept: https://simple.wikipedia.org/wiki/Aleph_null
Infinity is defined as larger than any number, and larger is not
equal. Or, these sorts of
I was not surprised by the results.
What concept of _ do you have in ^:_ if not one of an “integer?”
Furthermore, (<: <: <.) *. (>: >: >.) is true for any numeric value.
I think it’s obvious that _ is an identity to both (= <:) and (= >:)
– and so both <. and >. must return _ as well (likewise
Sorry, not
“_ is an identity to both (= <:) and (= >:)“
but
“ _ and __ are identities to bot <: and >:”
or
“_ and __ are the only values satisfying both (= <:) and (= >:)”
… except for NaN (_.), but that’s not exactly the topic here I think.
Am 02.08.20 um 12:52 schrieb Hauke Rehr:
I was not
Oops.
> Let <. : R+ -> Z+ where (<.r) is defined to be the extended integer such
> that there exists a real number s in the interval [0,1) and ((<.r)=|s-r).
((<.r)=|s-r) should be ((<.r)=r-s).
--
For information about J
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:
I think you mean "finds elements of a list which would be
representable exactly as either integers or booleans". Typically, your
list will be all floating point numbers. But, also, I do not think you
want to exclude 1 nor 0.
This boils down to a test for fractionality with a range test.
In many
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