On reflection, this is clearly a bug since the exact float 2^63 is a
better approximation than any integer. I'll fix it.
Henry Rich
On 10/23/2021 10:39 AM, ethiejiesa via General wrote:
Note, this issue is not specific to based representations. 9223372036854776064
(i.e. INT_MAX+256) also parses to INT_MAX with integer precision. I just used
hex in my examples since it makes bit boundaries a lot more obvious.
Raul Miller <[email protected]> wrote:
There are currently three "constants" pages in the wiki:
https://code.jsoftware.com/wiki/Vocabulary/Nouns
https://code.jsoftware.com/wiki/Vocabulary/Constants
https://code.jsoftware.com/wiki/Guides/Constants
I have updated the Guides/Constants page, as it already had a segment
on 'based' constants.
I am not sure about the Vocabulary/Constants page -- it looks like it
needs a lot of work. Perhaps a redirect might be a better option?
The Vocabulary/Nouns page covers a larger suite of topics and is
probably not the right place for this kind of detail.
Thanks,
--
Raul
On Sat, Oct 23, 2021 at 8:59 AM Ian Clark <[email protected]> wrote:
I was just about to say that, Henry.
Ancillary pages are intended to be linked from multiple NuVoc pages. I
thought there might be a need for a new one to address the matter of this
thread. But [[Vocabulary/Constants]]
https://code.jsoftware.com/wiki/Vocabulary/Constants
seems to be its natural home for now.
Note that the last section:
https://code.jsoftware.com/wiki/Vocabulary/Constants#Further_reading
promises to answer Raul's question, but links to a missing page …or is it a
placeholder?
Some NuVoc pages link into Pipermail, as a temporary measure, until someone
has the time to draw threads together.
For forum members who haven't used Pipermail, the link to the present
thread is:
https://www.jsoftware.com/pipermail/general/2021-October/038701.html
On Sat, 23 Oct 2021 at 13:44, Henry Rich <[email protected]> wrote:
Constants
Henry Rich
On Sat, Oct 23, 2021, 2:03 PM Raul Miller <[email protected]> wrote:
I guess the question is: which wiki page should this be documented in?
(If it's not already -- I guess another question is what should I
search on to attempt to find such documentation?)
Thanks,
--
Raul
On Sat, Oct 23, 2021 at 5:44 AM Henry Rich <[email protected]> wrote:
You might have a point, but I don't think it's worth taking the risk of
breaking existing code to make the change. If you want a float, add a
decimal point.
Numbers close to IMAX are always troublesome because of tolerance.
Henry Rich
On 10/23/2021 4:13 AM, ethiejiesa via General wrote:
The issue I find surprising is that integer literals in the range
16b8000000000000000 to 16b80000000000004ff, i.e. INT_MAX+1 to
INT_MAX+1024, all
parse into the integer precision 9223372036854775807, i.e. INT_MAX.
This is not
the same thing as (<:2^63) which has floating precision.
My expectation was that non-exact representations for (2^63x) and
above---
e.g. 16b8000000000000000---would parse into floating precision
numbers.
As it stands, this means that integer precision values equal to
16b7fffffffffffffff cannot be trusted and must be handled specially,
as
demonstrated nicely in Raul's examples below.
Henry Rich <[email protected]> wrote:
16b8000000000000401 cannot be exactly represented. There is a band
of floats near 2^63 that are converted to (<:2^63).
Henry Rich
On 10/23/2021 1:42 AM, Raul Miller wrote:
I do not see why I should expect these to be the same number:
2^.92233720368547768323
66.3219
2^.16b8000000000000401
63
One is larger than can be represented using a 64 bit integer, and
so
datatype 92233720368547768323
floating
That said, I do think that there's a problem with the other one.
That
one is also larger than can be represented using a 64 bit signed
integer:
(2^63x)-16b8000000000000401
1
(2^63x)-16b8000000000000000
1
(2^63x)-16b7fffffffffffffff
1
So there's a certain range of numbers here which get treated ...
oddly.
Thanks,
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