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Maximizing

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> I'm looping over two variables to maximize a function, returning x and
> y that maximize f.  Any way to do it without the setf in the body?
> 
> ; Here's a function you can paste to the REPL.
> 
> (defun f (x y)
>   (- (+ (* 9 x) (* 4 y))
>      (* x x)
>      (* y y))

A parenthesis is missing.

> 
> ; And here's what I'm trying to do:
> 
> (let ((best-x -1)
>       (best-y -1)
>       (max nil))
>   (loop :for x :below 10 :do
>         (loop :for y :below 10 :do
>               (let ((n (f x
> y)))
>                 (if (or (null max) (> n
> max))
>                     (setf best-x
> x
>                           best-y
> y
>                           max n)))))
>   (values best-x best-y))

Ruby:

def f x,y; 9*x+4*y-x*x-y*y; end

a=(0..9).to_a
a.product(a).max_by{|x| f *x}
 ===>
[4, 2]

In Forth?


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Maximizing "Robert L." <No_spamming@noWhere_7073.org> - 2016-12-10 21:36 +0000
  Re: Maximizing jean-pierre@buechi-schmitt.ch - 2016-12-10 14:21 -0800

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