correction : 'will be the <last> number of the sequence'
in any case for a special number the real root will be an integer.
On 06/08/2015 4:06 PM, Don Kelly wrote:
also try
0=1|( <1; 2) {>p.|.1 3 2,-]720
1_
0=1|( <1; 2) {>p.|.1 3 2,-]719
0
note that
(<1;2) {>p._y 2 3 1
will return an integer for a special number and this will be the first
number of the sequence
based on x*x+1)*(x+2) -y=0 giving an integral root
p._720 2 3 1
┌─┬────────────────────────────┐
│1│_5.5j7.72981 _5.5j_7.72981 8│
└─┴────────────────────────────┘
a modification to x(x^2-1) gives an integral real root for the middle
root
p. _720 _1 0 1
┌─┬────────────────────────────┐
│1│9 _4.5j7.72981 _4.5j_7.72981│
└─┴────────────────────────────┘
puts the real root first rather than last
As for finding a list of these special numbers-the "stope " function
works well
f=:3^!.1~[:i.]
f 10
0 6 24 60 120 210 336 504 720 990
Don Kelly
On 06/08/2015 1:02 PM, Roger Hui wrote:
g=: = (^&3 - ])@:(3&(>.@%:))
g */"1 (10^40 60 80x)+/0 1 2
1 1 1
On Thu, Aug 6, 2015 at 11:23 AM, 'Pascal Jasmin' via Programming <
[email protected]> wrote:
(] = (^&3 - ])@:(1r3 >.@^~ ])) 990
----- Original Message -----
From: Kip Murray <[email protected]>
To: "[email protected]" <[email protected]>
Cc:
Sent: Thursday, August 6, 2015 1:58 PM
Subject: [Jprogramming] Detecting special products
The number 720 is special: it is 8*9*10 the product of three
successive non-negative integers. The first few special numbers are
*/"1 [ 0 1 2 +"1 0 i. 10
0 6 24 60 120 210 336 504 720 990
Write a verb test that tests whether a non-negative integer is
special:
test 720
1
test 0
1
test 721
0
--Kip Murray
--
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