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=unavailable autolearn_force=no version=3.4.4
X-Received: by 10.99.5.147 with SMTP id 141mr3000264pgf.3.1478993415548;
        Sat, 12 Nov 2016 15:30:15 -0800 (PST)
X-Received: by 10.157.37.247 with SMTP id q110mr833923ota.5.1478993415508;
 Sat, 12 Nov 2016 15:30:15 -0800 (PST)
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!news.glorb.com!q124no179953itd.0!news-out.google.com!x12ni1812ita.0!nntp.google.com!q124no179947itd.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
Newsgroups: comp.lang.ada
Date: Sat, 12 Nov 2016 15:30:15 -0800 (PST)
In-Reply-To: <d7ea2e53-23a8-4b68-bce0-ab3d245a1fb0@googlegroups.com>
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=76.218.37.33;
 posting-account=W2gdXQoAAADxIuhBWhPFjUps3wUp4RhQ
NNTP-Posting-Host: 76.218.37.33
References: <d7ea2e53-23a8-4b68-bce0-ab3d245a1fb0@googlegroups.com>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <ac89f4e4-0106-42dc-8ec3-a9cfef91f9db@googlegroups.com>
Subject: Re: matrix manipulation
From: Stephen Leake <stephen_leake@stephe-leake.org>
Injection-Date: Sat, 12 Nov 2016 23:30:15 +0000
Content-Type: text/plain; charset=UTF-8
Xref: news.eternal-september.org comp.lang.ada:32296
Date: 2016-11-12T15:30:15-08:00
List-Id: <comp.lang.ada>

On Saturday, November 12, 2016 at 12:16:47 PM UTC-6, hn...@yahoo.de wrote:
> What is an elegant way to program exchange of columns in a matrix. 
> Application: 
> C is a matrix. Cj be the j-th column of C.
> Sort C1,C2, ..., Cn in non increasing order with respect to their first component.
> I tried and ended up in a very messy program, as I had to sort the first components first, remember their new index and then reconstruct the matrix.

declare the matrix as an array of columns:

type Column is array (1 .. 10) of float;
type Matrix is array (1 .. 10) of Column;

A : Matrix := ...;
Tmp : Column;

Tmp := A (2);
A (2) := A (1);
A (1) := Tmp;