9.3x
|ill-formed number

could, it instead "parse" to

93r10

?


________________________________
From: Henry Rich <henryhr...@gmail.com>
To: Programming forum <programm...@jsoftware.com> 
Sent: Friday, August 11, 2017 5:11 AM
Subject: [Jprogramming] 4 <3!:0 <. y WAS: Integer-floating type change for 
large numbers in j805 and j806



The error, methinks, is that 999...9. is rounded to integer and then

reported as integer.   It should keep floating type.


Bit-twisting code needs to be sure that no bits have been lost.   Integral

type should be a guarantee of that.  Floats that have values

unrepresentable accurately should not be automatically called ints.


Henry Rich


On Aug 11, 2017 06:14, "Don Kelly" <d...@shaw.ca> wrote:


isn't an advantage of APL and J that the person writing a

program/app/whatever, doesn't   have to deal with the distinctions between

integer and damn near integer  within the limitations of the computer

binary resolution?. In most cases this isa good thing because close enough

-given the +/- of data input is sufficient for the idiot box to decide. J

moves away from C/C++/ and other languages which often seem to be

emphasizing stuff that Iverson tried to eliminate in APL and J . Muh of

that stuff is something that can be handled by the idiot box so that:


Problem-->basic analysis--. coding that fits the analysis rather than the

details( users aim at the essentials rather than the details- "/I  want the

answer and I dont care about what is involved in the background of %,*

*/


The discussion below deals with representation of numeric values being

floating point or integer when pushing the limits-IS IT IMPORTANT IN THE

REAL WORLD unless  you have a Cray in the back bedroom?


Old fart expressing opinions


Don Kelly



On 2017-08-10 6:27 PM, Bill wrote:


> I suspect J interpreter didn't has the knowledge  that the original string

> had been 9999999999999999.3

> with .3 because what J saw was the floating point result of parsing by c

> library. Ieee floating point has 15 to 16 significant digits so that 1e16

> and 1e16-1 is the same number.

>

> Perhaps one could use long double to parse number on J64.

>

> Sent from my iPhone

>

> On 10 Aug, 2017, at 3:48 AM, Henry Rich <henryhr...@gmail.com> wrote:

>

> Quite right.

>>

>> Henry Rich

>>

>> On Aug 9, 2017 20:46, "Raul Miller" <rauldmil...@gmail.com> wrote:

>>

>> Well, since it's encoded as an integer (which I would have noticed if

>>> I had read Bob Therriault's original post more closely), and not [like

>>> I was thinking] a float, I agree that dropping the .3 is better than

>>> adding a 1.

>>>

>>> That said, I guess we also should not object too loudly if

>>> 9999999999999999.3 were instead encoded the same as

>>> 9999999999999999+0.3 gets encoded.

>>>

>>> Thanks,

>>>

>>> --

>>> Raul

>>>

>>> On Wed, Aug 9, 2017 at 3:25 PM, Henry Rich <henryhr...@gmail.com> wrote:

>>>

>>>> Surely integer 999...9 is a better value than 1000...0 .

>>>>

>>>> Henry Rich

>>>>

>>>> On Aug 9, 2017 18:33, "Raul Miller" <rauldmil...@gmail.com> wrote:

>>>>

>>>> It's not a bug, it's an artifact of the 64 bit floating point standard.

>>>>>

>>>>>    2 ^.9999999999999999

>>>>> 53.1508

>>>>>

>>>>> https://en.wikipedia.org/wiki/IEEE_754#Basic_and_interchange_formats

>>>>>

>>>>> The binary64 format has 53 binary digits or 15.95 decimal digits. This

>>>>> means ".16#'9' cannot be represented exactly using this format.

>>>>>

>>>>> And, we do not use exact representation of large numbers by default

>>>>> because that's too slow for large datasets. Put differently, if you

>>>>> want exact representation and are willing to take the performance hit,

>>>>> you should specify that. For example: ".'x',~16#'9' or

>>>>> ".'3r10+','x',~16#'9'

>>>>>

>>>>> Thanks,

>>>>>

>>>>> --

>>>>> Raul

>>>>>

>>>>> On Wed, Aug 9, 2017 at 12:05 PM, Henry Rich <henryhr...@gmail.com>

>>>>>

>>>> wrote:

>>>

>>>> This is a bug,  since 999...9.3 should become 999...9 rather than

>>>>>>

>>>>> 100...0.

>>>>>

>>>>>> I'm away from home now,  but I think what's happening is this:

>>>>>>

>>>>>> 999...9 is converted to integer

>>>>>>

>>>>>> . is encountered and turns it to float

>>>>>>

>>>>>> It's rounded to the nearest float which is 100...0

>>>>>>

>>>>>> As a final step the JE checks to see if the value is exactly integral,

>>>>>> which it is,  and it is converted back to integer.

>>>>>>

>>>>>> If you add this to Interpreter/Bugs I'll fix it when i get back.

>>>>>>

>>>>>> Henry Rich

>>>>>>

>>>>>> On Aug 9, 2017 16:16, "bill lam" <bbill....@gmail.com> wrote:

>>>>>>

>>>>>> I think this is the difference between 32 and 64-bit,

>>>>>>

>>>>>>    9!:14''

>>>>>> j602/2008-03-03/16:45

>>>>>>    3!:0[ 9999999999999999.3

>>>>>> 4

>>>>>>

>>>>>> In J32

>>>>>>

>>>>>>    a.i. 2 fc 9999999999999999.3

>>>>>> 0 128 224 55 121 195 65 67

>>>>>>    a.i. 2 fc 1e16

>>>>>> 0 128 224 55 121 195 65 67

>>>>>>

>>>>>> the number has the same bit pattern as 1e16 (an integer)

>>>>>> which can be represented as a 64-bit integer. I guess

>>>>>> J64 is correct since 9999999999999999.3 and 1e16 is the

>>>>>> same number in ieee fp and J prefers integer to floats,

>>>>>> eg

>>>>>>   3!:0 [ 2.0

>>>>>> 4

>>>>>>

>>>>>> Ср, 09 авг 2017, robert therriault написал(а):

>>>>>>

>>>>>>> Hi Pascal,

>>>>>>>

>>>>>>> I see the same behaviour in j806 as j805. Do you see something

>>>>>>>

>>>>>> different?

>>>>>

>>>>>>     JVERSION

>>>>>>> Engine: j806/j64avx/darwin

>>>>>>> Beta-4: commercial/2017-06-27T12:55:06

>>>>>>> Library: 8.06.03

>>>>>>> Qt IDE: 1.5.3/5.6.2

>>>>>>> Platform: Darwin 64

>>>>>>> Installer: J806 install

>>>>>>> InstallPath: /users/bobtherriault/j64-806

>>>>>>> Contact: www.jsoftware.com

>>>>>>>    (; datatype) 999999999999999.3

>>>>>>> ┌────┬────────┐

>>>>>>> │1e15│floating│

>>>>>>> └────┴────────┘

>>>>>>>    (; datatype) 9999999999999999.3

>>>>>>> ┌─────────────────┬───────┐

>>>>>>> │10000000000000000│integer│

>>>>>>> └─────────────────┴───────┘

>>>>>>>    (; datatype) 99999999999999999.3

>>>>>>> ┌──────────────────┬───────┐

>>>>>>> │100000000000000000│integer│

>>>>>>> └──────────────────┴───────┘

>>>>>>>    (; datatype) 999999999999999999.3

>>>>>>> ┌───────────────────┬───────┐

>>>>>>> │1000000000000000000│integer│

>>>>>>> └───────────────────┴───────┘

>>>>>>>    (; datatype) 9999999999999999999.3

>>>>>>> ┌────┬────────┐

>>>>>>> │1e19│floating│

>>>>>>> └────┴────────┘

>>>>>>>

>>>>>>> Cheers, bob

>>>>>>>

>>>>>>> On Aug 9, 2017, at 7:54 AM, 'Pascal Jasmin' via Programming <

>>>>>>>>

>>>>>>> programm...@jsoftware.com> wrote:

>>>>>>

>>>>>>> in j806,    9999999999999999.310000000000000000 probably the j805

>>>>>>>>

>>>>>>> behaviour is preferred.  If only for consistency.  But there may be a

>>>>>>

>>>>> good

>>>>>

>>>>>> reason for change.

>>>>>>

>>>>>>>      From: robert therriault <bobtherria...@mac.com>

>>>>>>>> To: Programming forum <programm...@jsoftware.com>

>>>>>>>> Sent: Wednesday, August 9, 2017 10:40 AM

>>>>>>>> Subject: [Jprogramming] Integer-floating type change for large

>>>>>>>>

>>>>>>> numbers

>>>

>>>> in j805 and j806

>>>>>>

>>>>>>> I am guessing that the following has something to do with

>>>>>>>>

>>>>>>> precision of

>>>

>>>> large numbers in j805 and is also true for j806.

>>>>>>

>>>>>>>   (; datatype) 999999999999999.3

>>>>>>>> ┌────┬────────┐

>>>>>>>> │1e15│floating│

>>>>>>>> └────┴────────┘

>>>>>>>>   (; datatype) 9999999999999999.3

>>>>>>>> ┌─────────────────┬───────┐

>>>>>>>> │10000000000000000│integer│

>>>>>>>> └─────────────────┴───────┘

>>>>>>>>   (; datatype) 99999999999999999.3

>>>>>>>> ┌──────────────────┬───────┐

>>>>>>>> │100000000000000000│integer│

>>>>>>>> └──────────────────┴───────┘

>>>>>>>>   (; datatype) 999999999999999999.3

>>>>>>>> ┌───────────────────┬───────┐

>>>>>>>> │1000000000000000000│integer│

>>>>>>>> └───────────────────┴───────┘

>>>>>>>>   (; datatype) 9999999999999999999.3

>>>>>>>> ┌────┬────────┐

>>>>>>>> │1e19│floating│

>>>>>>>> └────┴────────┘

>>>>>>>>   JVERSION

>>>>>>>> Engine: j805/j64/darwin

>>>>>>>> Release: commercial/2016-12-11T08:17:56

>>>>>>>> Library: 8.05.14

>>>>>>>> Qt IDE: 1.5.4/5.6.2

>>>>>>>> Platform: Darwin 64

>>>>>>>> Installer: J805 install

>>>>>>>> InstallPath: /applications/j64-805

>>>>>>>> Contact: www.jsoftware.com

>>>>>>>>

>>>>>>>> Further investigation shows me it was not this way with the 32 bit

>>>>>>>>

>>>>>>> version of j701, so it may be an artifact of moving to 64 bit?

>>>>>>

>>>>>>>       (; datatype) 999999999999999.3

>>>>>>>> ┌────┬────────┐

>>>>>>>> │1e15│floating│

>>>>>>>> └────┴────────┘

>>>>>>>>   (; datatype) 9999999999999999.3

>>>>>>>> ┌────┬────────┐

>>>>>>>> │1e16│floating│

>>>>>>>> └────┴────────┘

>>>>>>>>   (; datatype) 999999999999999999.3

>>>>>>>> ┌────┬────────┐

>>>>>>>> │1e18│floating│

>>>>>>>> └────┴────────┘

>>>>>>>>   (; datatype) 9999999999999999999.3

>>>>>>>> ┌────┬────────┐

>>>>>>>> │1e19│floating│

>>>>>>>> └────┴────────┘

>>>>>>>>   JVERSION

>>>>>>>> Engine: j701/2011-01-10/11:25

>>>>>>>> Library: 7.01.088

>>>>>>>> Platform: Darwin 32

>>>>>>>> Installer: j701a_mac_intel.dmg

>>>>>>>> InstallPath: /Applications/j701

>>>>>>>>

>>>>>>>> Cheers, bob

>>>>>>>>

>>>>>>>>

>>>>>>>>

>>>>>>>> ------------------------------------------------------------

>>>>>>>>

>>>>>>> ----------

>>>>>

>>>>>> For information about J forums see http://www.jsoftware.com/

>>>>>>>>

>>>>>>> forums.htm

>>>>>

>>>>>>

>>>>>>>> ------------------------------------------------------------

>>>>>>>>

>>>>>>> ----------

>>>>>

>>>>>> For information about J forums see http://www.jsoftware.com/

>>>>>>>>

>>>>>>> forums.htm

>>>>>

>>>>>> ------------------------------------------------------------

>>>>>>>

>>>>>> ----------

>>>

>>>> For information about J forums see http://www.jsoftware.com/

>>>>>>>

>>>>>> forums.htm

>>>

>>>> --

>>>>>> regards,

>>>>>> ====================================================

>>>>>> GPG key 1024D/4434BAB3 2008-08-24

>>>>>> gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3

>>>>>> gpg --keyserver subkeys.pgp.net --armor --export 4434BAB3

>>>>>> ------------------------------------------------------------

>>>>>>

>>>>> ----------

>>>

>>>> For information about J forums see http://www.jsoftware.com/

>>>>>>

>>>>> forums.htm

>>>

>>>> ------------------------------------------------------------

>>>>>>

>>>>> ----------

>>>

>>>> For information about J forums see http://www.jsoftware.com/

>>>>>>

>>>>> forums.htm

>>>

>>>> ----------------------------------------------------------------------

>>>>> For information about J forums see http://www.jsoftware.com/forums.htm

>>>>>

>>>> ----------------------------------------------------------------------

>>>> For information about J forums see http://www.jsoftware.com/forums.htm

>>>>

>>> ----------------------------------------------------------------------

>>> For information about J forums see http://www.jsoftware.com/forums.htm

>>>

>> ----------------------------------------------------------------------

>> For information about J forums see http://www.jsoftware.com/forums.htm

>>

> ----------------------------------------------------------------------

> For information about J forums see http://www.jsoftware.com/forums.htm

>


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