On Mon, 12 May 2003, Barry Margolin wrote:
Using the loop macro you can find the maximum of some numerical function
f, applied
to each element of a list by
(loop for x in list maxmimize (funcall f x))
But I want to return the x such that (funcall f x) is maximum
and I would like to write something like this:
(loop for x in list argmaximize (funcall f x))
Is there some loop keyword that would do this?
If there isn't such a keyword what's the most succinct way to
do this with the loop macro?
There isn't a keyword for it.
(loop with max-val = (car list)
for x in (cdr list)
when (> (funcall f x) max-val)
do (setq max-val x))
That doesn't function correctly.
Gauche Scheme:
(reduce
(lambda (a b) (if (> (square a) (square b)) a b))
'list-was-empty
'(2 -8 4 6))
===>
-8
That calls the function more times than necessary.
(define lst '(2 -8 4 6))
(fold
(lambda (a b)
(define res (square a))
(if (or (null? b) (> res (car b))) (list res a) b))
'()
lst)
===>
(64 -8)
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)