[Jprogramming] Recursive verbs

Fri Nov 30 06:18:13 UTC 2018

Here's a little variation. Fibonacci series begins 1 1 ...
Y=: ($:`)(`:6)
N=: 1 :'(u@:<:@:<: + [:u<:)^:(1 < ])'
N=: (5!:1)<'N'
}.N Y("0) i.11
1 1 2 3 5 8 13 21 34 55
Maybe there is a better way to drop the 0.
Linda
-----Original Message-----
From: Programming <programming-bounces at forums.jsoftware.com> On Behalf Of Linda Alvord
Sent: Wednesday, November 28, 2018 4:49 AM
To: programming at jsoftware.com
Subject: Re: [Jprogramming] Recursive verbs
Hi Cliff,
It took a while but I got the explicit verb to work.
f=: 13 :'4 p.~(([:(2&^)>:),.~ _1r3 *([:(2&^)>:) + _1&^)y' 
 
 f i.10
7 15 29 59 117 235 469 939 1877 3755
 
 f
4 p.~ ([: 2&^ >:) ,.~ _1r3 * ([: 2&^ >:) + _1&^
 
Linda
-----Original Message-----
From: Programming <programming-bounces at forums.jsoftware.com> On Behalf Of Cliff Reiter
Sent: Tuesday, November 27, 2018 12:38 PM
To: programming at jsoftware.com
Subject: Re: [Jprogramming] Recursive verbs
I like that solution. Here is another approach
  4 p.~(2&^@>: ,.~ _1r3 * 2&^@>: + _1&^)i. 10
7 15 29 59 117 235 469 939 1877 3755
I found this by composing the linear poly's and noting the constant terms satisfy a two step recursion with eigenvalues 2 and _1.
  lc=.({.@[+{:@[*{.@]),*&{:
  lc/\.(7$_1 2,:1 2)
_43 128
_21 64
_11 32
 _5 16
 _3  8
 _1  4
 _1  2
On 11/27/2018 11:06 AM, Raul Miller wrote:
> Sure, ... that's a bit bulkier than I prefer, but it works.
>> Here's another alternative:
>> evenodd=: , (_1 2,:_1 4)&p.@{:
> evenodd evenodd 4
> 4 7 15 29 59
>> Thanks,
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