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From: Goswin von Brederlow <goswin-v-b@web.de>
To: Dmitry Bely <dmitry.bely@gmail.com>
Cc: Caml List <caml-list@inria.fr>
Subject: Re: [Caml-list] Optimizing Float Ref's
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Date: Wed, 14 Apr 2010 20:13:55 +0200
In-Reply-To: <g2l90823c941003311218o21b3c207tfea7b3984f5ee93b@mail.gmail.com>
	(Dmitry Bely's message of "Wed, 31 Mar 2010 23:18:36 +0400")
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X-Spam: no; 0.00; ref's:01 val:01 val:01 mfg:98 rec:01 rewrite:01 recursively:01 dmitry:01 dmitry:01 caml-list:01 writes:01 bely:01 bely:01 len:02 len:02 

Dmitry Bely <dmitry.bely@gmail.com> writes:

> rewrite the function to get rid of it? My best achievement so far is
>
> let max_val (a:float array) =
>   let m = [|-.min_float|] in
>   for i = 0 to (Array.length a) - 1 do
>     if a.(i) > m.(0)
>     then m.(0) <- a.(i)
>   done;
>   m.(0)
>
> but it looks ugly...
>
> - Dmitry Bely

Why not store the index of the max element instead of the float itself?
Recursively, to avoid the ref as well, this could look like this:

let max_val (a:float array) =
  let len = Array.length a in
  let rec loop max i =
    if i = len
    then a.(max)
    else
      if a.(max) > a.(i)
      then loop max (i + 1)
      else loop i (i + 1)
  in
    if len = 0
    then -.min_float
    else loop 0 1

MfG
        Goswin