Re: Sum of squares

Newsgroups	comp.lang.forth
From	Albert van der Horst <albert@spenarnc.xs4all.nl>
Subject	Re: Sum of squares
Date	2012-03-28 11:41 +0000
Message-ID	<m1lf4n.9d@spenarnc.xs4all.nl> (permalink)
Organization	Dutch Forth Workshop
References	<10851509008435@frunobulax.edu> <m1jito.mmz@spenarnc.xs4all.nl>

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In article <10851509008435@frunobulax.edu>, Marcel Hendrix <mhx@iae.nl> wrote:
>Admit it (when trying it yourself), this exercise is
>surprisingly tricky.
>
>-marcel
<SNIP>
>
>  Define a procedure that takes three numbers as arguments and returns
>  the sum of the squares of the two larger numbers.

A much more interesting problem is the other way around:
Define a procedure that takes a prime 1 mod 4 and returns two squares
whose sum is that prime.

(It is known that there is exactly one solution.)

EXAMPLE

1,000,000,000,000,000,177 is a prime

These are the squares
  401586540284690721 598413459715309456

As you can check by

  633708561 SQ DUP . 773571884 SQ DUP . + .

It takes lina64 about 600 microseconds to find those.

Groetjes Albert

(Paraphrased because my previous post was too boring.)
--
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert@spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst

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Sum of squares mhx@iae.nl (Marcel Hendrix) - 2012-03-26 20:50 +0200
  Re: Sum of squares "A. K." <akk@nospam.org> - 2012-03-26 21:43 +0200
  Re: Sum of squares Paul Rubin <no.email@nospam.invalid> - 2012-03-26 16:52 -0700
    Re: Sum of squares Helmar Wodtke <helmwo@gmail.com> - 2012-03-27 03:15 -0700
      Re: Sum of squares Paul Rubin <no.email@nospam.invalid> - 2012-03-28 08:16 -0700
    Re: Sum of squares BruceMcF <agila61@netscape.net> - 2012-03-28 06:06 -0700
  Re: Sum of squares Zbiggy <zbigniew2011REMOVE@gmail.REMOVE.com> - 2012-03-27 12:13 +0100
    Re: Sum of squares Helmar Wodtke <helmwo@gmail.com> - 2012-03-27 04:03 -0700
      Re: Sum of squares Zbiggy <zbigniew2011REMOVE@gmail.REMOVE.com> - 2012-03-27 13:55 +0100
  Re: Sum of squares Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-03-27 11:05 +0000
    Re: Sum of squares Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-03-28 11:41 +0000
      Re: Sum of squares Paul Rubin <no.email@nospam.invalid> - 2012-03-28 07:41 -0700
      Re: Sum of squares mhx@iae.nl (Marcel Hendrix) - 2012-03-29 22:06 +0200
      Re: Sum of squares Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-03-31 11:48 +0000
    Re: Sum of squares Alexander Adler <alexander.adler@stud.uni-frankfurt.de> - 2012-03-29 19:33 +0200
      Re: Sum of squares Helmar Wodtke <helmwo@gmail.com> - 2012-03-29 11:16 -0700
        Re: Sum of squares Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-04-03 09:47 +0000
    Re: Sum of squares Helmar Wodtke <helmwo@gmail.com> - 2012-03-28 09:42 -0700
    Re: Sum of squares Helmar Wodtke <helmwo@gmail.com> - 2012-03-28 11:08 -0700
  Re: Sum of squares Ecki <ecki@intershop.de> - 2012-03-27 16:15 +0200
    Re: Sum of squares Helmar Wodtke <helmwo@gmail.com> - 2012-03-27 07:35 -0700
      Re: Sum of squares hwfwguy@gmail.com - 2012-03-27 08:00 -0700
        Re: Sum of squares Helmar Wodtke <helmwo@gmail.com> - 2012-03-27 08:21 -0700
        Re: Sum of squares Ecki <ecki@intershop.de> - 2012-03-29 09:05 +0200

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