I tried this in simple J. It should work in elementary school (as long as
it is correct)
f=: 13 :'(>:i.x) */>:i.y'
g=: 13 :'(i.x<.y)<:/i.x>.y'
all=: 13 :'+/,((x<.y) g x>.y) * (x<. y) f x >.y'
2 f 3
1 2 3
2 4 6
3 f 2
1 2
2 4
3 6
3 f 3
1 2 3
2 4 6
3 6 9
2 g 3
1 1
Here is another version of countRects
countRects=: */@(2 ! >:)
On Wed, Oct 8, 2014 at 9:07 AM, Tikkanz wrote:
> Sorry, yes that is a leap.
> (x * (x + 1)) * 0.5 is the number of ways to choose two horizontal lines
> to make 2 sides of the rectangle.
> (y * (y + 1)) * 0.5 is the number of ways to
Sorry, yes that is a leap.
(x * (x + 1)) * 0.5 is the number of ways to choose two horizontal lines to
make 2 sides of the rectangle.
(y * (y + 1)) * 0.5 is the number of ways to choose two vertical lines to
make the other 2 sides of the rectangle
((x * (x + 1)) * 0.5) * ((y * (y + 1)) * 0.5) is th
I got this:
countRects 77 36x
198
where I got the "77 36" from this:
({~ idxClosest@:(countRects"1)) getSizes >: i.200
77 36
On Tue, Oct 7, 2014 at 12:15 PM, 'Pascal Jasmin' via Programming <
programm...@jsoftware.com> wrote:
> countRects a cool solution that just works without my com
countRects a cool solution that just works without my complete understanding of
it either.
I'm not convinced of the getSizes range being used though:
this is pretty close to 2M
4 %~ */@(, >:) 3 816x
216
So I think a "triangulation" algorithm would be more general than the getSizes
fil
To answer Jon's last question, if "nr" is my matrix of results from
"countRects", then this gives me the index of the lowest (closest to 2e6)
in the raveled matrix:
(3 : '(] i. <./) ,y') 2e6(-|)nr
499
If we think of the indexes of a table as being a base ($table) number, we
can decode the vecto
Hi -
"countRects" seems like a bit of a leap. I think I understand "4 %~"
because you're overcounting by 4 rotations, but I don't comprehend the
magic behind "*/@(,>:)".
I see that "(,>:)" concatenates the shape to its increment, e.g. 2 3 3 4
for the input 2 3, but what's the rationale behind th
I don't know if my phone is 32 or 64 bit. But J is 32 bit.
On Oct 7, 2014 8:32 AM, "Don Guinn" wrote:
> I took your numbers and did
>
>256#.0 0 1 72 224 139 75 119
> 1412516498295
>
> on my laptop and phone and got the same answer. But it was an integer on
> my laptop and floating on my phone
Don - that works great. Thank you
_8 (] (256 #. ]) (a. i. ]))\ bin
or
times=: _8 (256 #. a. i. ])\ bin
On Tue, Oct 7, 2014 at 10:32 AM, Don Guinn wrote:
> I took your numbers and did
>
>256#.0 0 1 72 224 139 75 119
> 1412516498295
>
> on my laptop and phone and got the same answer.
I took your numbers and did
256#.0 0 1 72 224 139 75 119
1412516498295
on my laptop and phone and got the same answer. But it was an integer on my
laptop and floating on my phone. Might have to flip things around if you
have enian problems.
On Tue, Oct 7, 2014 at 8:23 AM, Joe Bogner wrote:
Thanks Don. It looks like a long on java is 64 bits, 8 bytes, even on a 32
bit architecture.
I'm uncertain of the right path forward. I could change the java app to log
a 4 byte timestamp, or I can figure out a way to convert the 8 byte to an
integer on J32.
The simplest change would be to have s
I checked IF64 on my phone and its value was zero. Help says that _3(3!:4)
only is valid for J64
On Tue, Oct 7, 2014 at 6:00 AM, Joe Bogner wrote:
> I have a android app that is logging sensor data to a text file using
> java's DataInputStream.writeLong[1]. It is logging a timestamp each
> time
I have a android app that is logging sensor data to a text file using
java's DataInputStream.writeLong[1]. It is logging a timestamp each
time it gets a step (pedometer). The timestamp comes from getTime()
[2]
I can read the file on Windows
bin=:fread 'c:/joe/j/steps.txt'
times=: |. _3 (3!:4) |.
Note that 200 x 200 is a bit of an overkill given 3x2 = 2x3
The following choses the lower triangular of a matrix of the different
sized rectangles to investigate.
getSizes=: ,@(>:/~) # [: ,/ ,"0/~
getSizes >: i. 5
Given the sides of a rectangle you can count the number of rectangles as
follows:
c
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