Earlier versions:
f=: 13 :'(; q:)@p.&10x@#&1@+&2 i.y'
g=: 13 : ' (;q:)"0}.+/\10^i.y'
f 4
------T------┐
│11 │11 │
+-----+------+
│111 │3 37 │
+-----+------+
│1111 │11 101│
+-----+------+
│11111│41 271│
L-----+-------
g 4x
-----T------┐
│11 │11 │
+----+------+
│111 │3 37 │
+----+------+
│1111│11 101│
L----+-------
(f 19)-:(g 20x)
1
Where did a line of the result go?
Linda
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Nick Simicich
Sent: Saturday, November 12, 2011 2:04 AM
To: Programming forum
Subject: Re: [Jprogramming] 11:11:11 repunits
e129rep2 =: 10 #. (1x $~ ])
e129rep 100
1111111111111111111111111111111111111111111111111111111111111111111111111111
111111111111111111111111
That is the one I use to make repunits....
Of course, this has the equivalent command line definition of
(10#. (1x $~ ]))
Thinking about it, this hook is a lot simpler looking and is equivalent, I
think.
e129rep =: 10&#. $&1x
(10&#. $&1x) 100
1111111111111111111111111111111111111111111111111111111111111111111111111111
111111111111111111111111
That leads to this variation:
(;q:)@(10&#. $&1x)"0 ]2+ i.18
I really like the cute little (;q:) - I would never have thought of it, I
suspect. The reason I like this phrase is that there is a lot of talk
about repunits in other bases, and this phrase is amenable to interpreting
the repunit numbers in other bases. For example, the same repunits, in base
5, but expressed in base 10:
(;q:)@:(5&#. $&1x)"0 >:>: i.18
5#.^:_1 ] 190734863281 NB. one of the numbers in the tables
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
and that leads to:
5b11111111111111111
190734863281
'5b',17$'1'
5b11111111111111111
".'5b',17$'1'
190734863281
Since J can accept literals in any base.
J's ability to accept input made up of numbers in other bases is cool. But
the only way I know of to express a number in, say, base 16, is to make a
verb that converts it to a string, and if you are "cute" about it, you can
cause the verb to be such that you can edit the output to use it in the
next calculation:
([: '16b'&, ([: {&'0123456789abcdefghijklmnop' 16&#.^:_1)) (16b89ee1791 +
16b54bfa75e)
tohex =: [: '16b'&, ([: {&'0123456789abcdef' 16&#.^:_1)
tohex 16b89ee1791 + 16b54bfa75e
or more generally,
tobase =: dyad : '([:((":x),''b'')&, ([: {&''0123456789abcdefghijklmnop''
x&#.^:_1)) y'
11 tobase 11111111111
11b4791a29261
11 tobase 11b111111111
11b111111111
(I'm sure I've missed some sort of foreign construction that makes all
output appear in the base you want it to appear in, or some such. If there
is, maybe someone can elighten me?)
--
Of course I can ride in the carpool lane, officer. Jesus is my constant
companion.
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