Project Euler #66, extended precision integer square roots, no spoilers
Continuing the discussion, for which again thank you all: I found that what I
really wanted was large *integer* square roots. Since this seems to come up
frequently in Project Euler problems and since I believe there are E
Oops. Foolish error as I prepared for presentation. My apologies.
Here’s the accurate implementation of intsqrt.
intsqrt =: 3 : 0
NB. y An array of possible integer squares
NB. Return 0 for non-squares or integer roots
s * y = x: *: s =. <. 0.5 + x: 10 ^ -: x: 10 ^. y
)
Note that it is explici
You should have used
squares =: *: x: >: ? 1e5 $ 1e11
Computing the square using floating point and then converting to
extended precision means that many of your values in 'squares' are not
actually square.
For example:
x: *: 68824904566
4736867488519007764480
*: x: 68824904566
47368674
What keeps you from writing your comments vertically‽
Am 27.04.22 um 14:50 schrieb Ed Gottsman:
If J were written vertically, it might be easier to comment.
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Fo
For what it's worth, J could easily be written vertically. But that's
probably not quite what people would want.
vertical=: {{ 0!:0;:inv{.@;:;._2 m}}
{{)n
mean
=:
+
/
%
#
}}vertical
mean 1 2 3
2
--
Raul
On Wed, Apr 27, 2022 at 2:01 PM Hauke Rehr wrote:
>
> Wha
I thought what was wanted was to write the _comments_ vertically, as in:
mean=: +/ % #
NB. i sr d l
NB. s ue i e
NB.md v n
NB. u i g
NB. c d t
NB. t e h
NB. i d
NB. o
NB. n b
NB. y
On Wed, 27 Apr 2022, Raul Miller wrote:
For what it's worth, J could easily
Probably more like
vert=: {{0!:0;:inv@;;.1 a:,<@}:@;:@,&' NB.';._2 m}}
{{)n
NB. y Possible squares of integers. Return either integer
NB. square roots or 0s.
intsqrt=: {{
y
* NB. Multiply to produce either integer square roots or 0s
y
= NB. 1s where the calculated square
Present: Art Anger, Devon McCormick, Raul Miller, Bob Therriault
• A discussion of the J playground and the progress that it is making.
Wondering about the value of creating a video that outlines a good process for
users to provide feedback in the process.
• A discussion about vi
LOL. Fair question. Here’s another: if J adopted a style standard around
ideograms (which are rendered vertically by default) for comments, would that
on the one hand slightly increase (as a percentage) its reputation for
obscurity among Western programmers but on the other dramatically increa
Raul,
D’oh. *Sigh*. It helps. Many thanks. I appreciate your patience as much as
your knowledge and willingness to help.
Ed
Sent from my iPad
> On Apr 27, 2022, at 3:36 PM, Raul Miller wrote:
>
> You should have used
> squares =: *: x: >: ? 1e5 $ 1e11
>
> Computing the square using f
The LEO editor might be a good fit.
And yes, it’s really freaking (cool).
A script could generate the actual .ijs from snippets that are well
documented and those snippets may well be single J tokens.
Am 28.04.22 um 08:10 schrieb Ed Gottsman:
LOL. Fair question. Here’s another: if J adopted a
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