June Kim wrote:
> NB. times per year
> tpy=:conjunction : (':';' (x%u) v (y*u) ')
> (2000*(1+0.095%3)^3*5)-: 2000 at 9.5 percent 3 tpy compoundfor 5
years
I don't have anything major to contribute here, but note that
I prefer to follow the m vs. u argument convention, where I use
m if I expect the argument to be a noun.
tpy1=:conjunction : (':';' (x%m) v (y*m) ')
But I'd also prefer that tpy produce an intermediate
result which doesn't literally quote the body of tpy.
tpy2=:conjunction : (':';' ([%m[]) v (]*m[]) ')
Of course, that's a bit verbose. Since the result
is now a verb distinct from the conjunction we don't
need ':' any more:
tpy3=:conjunction : ' ([%m[]) v (]*m[]) '
Also, we could make that shorter by commuting the arguments
and discarding some irrelevant punctuation
tpy4=:conjunction :'(m%~[) v m*]'
Also, I should mention if I felt it was important to have
'years' as an identity adverb, I think I'd also want 'annually'
as an identity adverb.
This would make the above expression even more verbose
('percent annually', rather than 'percent') and bury
the significant operations even deeper, but that might
not matter, depending on target audiences and intended
applications.
(Personally, I find the J expressions (such as on the left
side of -: above) easier to digest than the more verbose
statements (such as on the right side of -: above).)
Presenting both side by side could be good, depending
on the audience, but from my point of view both the
concepts and the results are important, and they work
together. The results illustrate the concepts and the
concepts make the results relevant.
Thus,
(1+0.05%12)^12
1.05116
5 percent annually 12 timesPerYear compoundFor 1 year
1.05116
and
12 timesPerYear compoundFor f.
(12 %~ [) (>:@[ ^ ]) 12 * ]
Note: in principle, J might have rearranged
that verb so that it displays as >:@(12 %~ [) ^ 12 * ]
But other changes might also be a good idea:
To my way of thinking, 5 percent annual interest compounded
12 times per year should correspond to a monthly interest
of 1.05^%12 -- that it does not says something about
banking practices, and about the verbal shortcuts that have
come to be accepted as standard.
I'm not sure how best to express all these concepts in English,
on an expression-by-expression basis, and usually I don't try.
In other words: while this is probably a worthy subject,
I think the implicit assumptions are the trickiest aspect
of the issue.
--
Raul
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
