On Thu, 21 Apr 2022, Michal Wallace wrote:
I then thought that replacing u => [. and v => ]. would let me remove the
double curlies, but clearly this is the wrong idea:
AA =: ([. @: ].) ]. ]
_: AA (3 AT) ;/i.10
+-+-+-+-+-+-+-+-+-+-+
|0|1|2|3|4|5|6|7|8|9|
+-+-+-+-+-+-+-+-+-+-+
I don't real
Thanks, Elijah! This was very helpful.
I think I was sort of hallucinating that the mere presence of [. and ].
would change the meaning of the entire train,
the way the mere presence of u and v changes the meaning of a direct
definition, but of course that's not the case.
I am going to have to m
> (].~)@:
It is the CC train. The @: will bind to u@:v
(].~) is CA (so still part of overall CC train (CA)C is CC)
]. ignores u, and so (].~) is v~
On Thursday, April 21, 2022, 10:35:41 a.m. EDT, Michal Wallace
wrote:
Thanks, Elijah! This was very helpful.
I think I was sort of
Hello.
I’m working on the Project Euler “Diophantine equation” problem (#66) and using
J’s extended precision facilities. I’ve run into behavior that confuses me.
Boiled down (and overusing x: just to be sure):
x: %: x: 1 + x: *: x: 9
9
That is (if my syntax is right),
3!:0 %: x: 1 + x: *: x: 9
8
The square root cannot be represented exactly.
Henry Rich
On 4/21/2022 12:43 PM, Ed Gottsman wrote:
Hello.
I’m working on the Project Euler “Diophantine equation” problem (#66) and using J’s extended precision facilities. I’ve run into behavior that c
Square root does not produce an extended precision result.
<.@%: does produce an extended precision result, but that would not
resolve your problem here.
FYI,
--
Raul
On Thu, Apr 21, 2022 at 12:43 PM Ed Gottsman
wrote:
>
> Hello.
>
> I’m working on the Project Euler “Diophantine equation” pro
Ed
You seem unaware of the extended precision constant notation:
"digits with a trailing x denote an extended precision integer"
https://www.jsoftware.com/help/dictionary/dcons.htm
[Where is the equivalent in NuVoc?]
I would rather write
1x + *: 9x
82
~ Gilles
Le
Gilles,
In Nuvoc the extended constant notation can be found here
https://code.jsoftware.com/wiki/Vocabulary/Constants#Extended_Integers
Having said that, it is hidden pretty well and most of its references are
previous documentation on the jsoftware site. There is certainly work to be
done on
Ed If you expand the Extended Integers section (below by bob), you will
see a link to an essay by Roger on 'Extended Precision Functions'. There
is a Square Root verb.
NB. long rational result may exceed line length
sqrt 1x + *: 9x
1249987500062500625004687515
Showing the result in decimal:
23j13": sqrt 1x + *: 9x
9.05000
On Thu, Apr 21, 2022 at 3:18 PM Gilles Kirouac wrote:
> Ed If you expand the Extended Integers section (below by bob), you will
> see a link to an essay by Roger on 'Extended Precision Functions'. There
>
One way to obtain high precision roots is to use, say, Newton’s solution to
y = x^2 - a :
Given an estimate x(n-1), the next estimate is
xn = x(n-1) - y/(dy/dx), in Maths notation.
In J, (J701 on this iPad),
rt =: -:@] + (% +:) NB. x is number whose root is required, y an initial
guess
Thanks to everyone who responded and in particular for the link to Roger Hui’s
essay. The wiki discussion was also very good.
(In an earlier life I disparaged “cargo cult” programming, in which you take a
few lines of source you don’t understand and integrate them into your program.
[That you
Hi Ed,
I was thinking of explaining Roger's sqrt code as part of next month's
NYCJUG.
You should take a look:
https://www.meetup.com/J-Dynamic-Functional-Programming/ .
Cheers,
Devon
On Fri, Apr 22, 2022 at 12:49 AM Ed Gottsman
wrote:
> Thanks to everyone who responded and in particular for the
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