[Jprogramming] &. in primes-under-ten-thousand

[Roger Hui]

In addition to Raul Miller's comments, the 
dictionary page for ^: says that:

p:^:_1 n gives the number of primes less than n, denoted by pi(n) in math

http://www.jsoftware.com/help/dictionary/d202n.htm



----- Original Message -----
From: Tracy Harms <tharms at symantec.com>
Date: Monday, March 5, 2007 10:03 am
Subject: [Jprogramming] &. in  primes-under-ten-thousand

> Raul Miller replied to Geoff Canyon:
>
>>> based on a calculation? For example, suppose I want to generate all
> 
>>> the primes < 10,000.
> 
>>    i.&.(p:^:_1)10000

> 
> Attempting to think this through, the difficulty I am having is in 
> understanding the obverse of (p:^:_1), i.e. the  vi  portion of 
> the equivalency documented under monadic under.
> 
> u&.v y &#8596; vi u v y
> 
> Illumination would be appreciated!