Your problem is that "vary" is fixed when it's
defined. The random number is evaluated only
when (& whenever) you define "vary".
eg from a J session:
vary =: +&(?10) NB. define it
vary NB. display it
+&4
vary^:(i.5) 10 NB. run it
10 14 18 22 26
vary =: +&(?10) NB. 2nd try
vary
+&3
vary^:(i.5) 10
10 13 16 19 22
vary =: +&(?10) NB. 3rd try
vary
+&6
vary^:(i.5) 10
10 16 22 28 34
One way to achieve what you evidently require
is
vary =: 10 & (13 : 'y+?x')
vary
10&(] + [: ? [)
vary^:(i.5) 10
10 13 21 24 28
although I'd usually use an array approach, eg:
10 + ?5#10
10 11 14 19 10
Mike
On 23/03/2011 11:43, Adrian May wrote:
> Hi folks,
>
> You probably already guessed what the problem is. I want to write something
> like:
>
> n=.100
> vary =. +&(?10)
> n=.vary n
> n
> n=.vary n
> n
> n =. vary^:10 (100)
> n
>
> but it only evaluates the ? once and reuses that value. I want a different
> number every time. How do I do that?
>
> Adrian.
>
> PS: I was hoping to keep my whole program to one line just to scare people.
> It seems to work better in a function but even then I have problems
> sometimes. What's the logic behind whether it re-evaluates ? or not?
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