From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,b2923d60cb81694b
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!postnews.google.com!64g2000cwx.googlegroups.com!not-for-mail
From: "Adam Beneschan" <adam@irvine.com>
Newsgroups: comp.lang.ada
Subject: Re: Unsigned Integer Restraint Errors
Date: 13 Mar 2007 09:04:14 -0700
Organization: http://groups.google.com
Message-ID: <1173801854.505211.245650@64g2000cwx.googlegroups.com>
References: <1173712032.183064.264340@8g2000cwh.googlegroups.com>
   <e9in1ny6b3gb.16e7shcfhyja8$.dlg@40tude.net>
   <1173726806.656979.305660@8g2000cwh.googlegroups.com>
   <et4cma$o0v$1@jacob-sparre.dk>
   <BFoJh.14542$PF.8157@attbi_s21>
   <et57ho$bjm$1@jacob-sparre.dk>
   <1173787790.826099.287610@s48g2000cws.googlegroups.com>
   <1173797935.875023.7590@p10g2000cwp.googlegroups.com>
NNTP-Posting-Host: 66.126.103.122
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
X-Trace: posting.google.com 1173801860 31301 127.0.0.1 (13 Mar 2007 16:04:20
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Tue, 13 Mar 2007 16:04:20 +0000 (UTC)
In-Reply-To: <1173797935.875023.7590@p10g2000cwp.googlegroups.com>
User-Agent: G2/1.0
X-HTTP-UserAgent: Mozilla/5.0 (X11; U; Linux x86_64; en-US;
 rv:1.7.12) Gecko/20050922 Fedora/1.7.12-1.3.1,gzip(gfe),gzip(gfe)
Complaints-To: groups-abuse@google.com
Injection-Info: 64g2000cwx.googlegroups.com; posting-host=66.126.103.122;
   posting-account=cw1zeQwAAABOY2vF_g6V_9cdsyY_wV9w
Xref: g2news1.google.com comp.lang.ada:14513
Date: 2007-03-13T09:04:14-07:00
List-Id: <comp.lang.ada>

On Mar 13, 7:58 am, "frikk" <frik...@gmail.com> wrote:
> I have a bit of an unrelated (but kind of related) question:
>
> Are there any builtin square root functions? I thought this was
> working, but I don't think it is anymore:
> m := Integer(100**(0.5)+1);

This couldn't have worked as written, since there is no predefined
"**" that accepts a floating-point number on the right side.

> This always coming out to 2. I;m using this to computer a maximum loop
> value for finding primes. I'd like to loop from 2 to sqrt(n)/2 + 1.
>
> Any suggestions?

See Section A.5.1.  Ada.Numerics.Elementary_Functions (A.5.1(9))
defines Sqrt as well as a "**" that accepts floating-point exponents.

By the way, if I were going to write a loop that goes from 2 to
sqrt(n)/2 + 1, I wouldn't use Sqrt like this:

    for I in 2 .. Integer(Float'Floor(Sqrt(Float(N))/2.0)) + 1 loop...

but rather, I'd just write it something like this:

    I := 2;
    while (2 * I - 1) * (2 * I - 1) <= N loop -- I think I got this
right
        ...
        I := I + 1;
    end loop;

on the theory that using Sqrt is just a waste of cycles when you can
just use integer arithmetic.  But I've been programming for way too
long---long enough that I remember what a Hollerith card is---and I'm
sure that doing a square-root doesn't take nearly as long as it used
to, so there are probably some reasonable values of N for which
computing the square-root first makes things more efficient than the
repeated integer multiplications.  I don't know.  Use Sqrt if you want
to.

                                 -- Adam