[Jprogramming] special coding for stack operations

[greg heil]

On 7/12/06, R&S HUI <rhui000 at shaw.ca> wrote:
> What exactly is "swap"?  Is it  name=: (<i,j) C. name  ?

In this context it is as

On 7/12/06, Miller, Raul D <rdmiller at usatoday.com> wrote:
> Using the right hand edge of a list as top of stack:
>    swap=: _2 (}. , |.@{.) ]

However it is interesting you asked, as i have been trying to develop
an efficient generalization, which i have been calling swap, that
reverses arbitrary elements in an array. Eg defined as

reverse=:[:|.{	NB. reverse of x{y
amend=: 1 : 'u`[`]}'	NB. amend x{y with u of x{y
swapG=: reverse amend
   (1 2; 2 0) swapG i.4 4
 0  1  2  3
 4  5  8  7
 6  9 10 11
12 13 14 15

But i am not clear on how to make this operation efficient, it is
currently a major fraction of the time budget for my application...

~greg