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Path: utzoo!watmath!watnot!watcgl!ksbooth
From: ksbooth@watcgl.UUCP (Kelly Booth)
Newsgroups: net.graphics
Subject: Re: bitmap rotation algorithm needed
Message-ID: <2809@watcgl.UUCP>
Date: Sat, 23-Nov-85 11:00:07 EST
Article-I.D.: watcgl.2809
Posted: Sat Nov 23 11:00:07 1985
Date-Received: Sun, 24-Nov-85 07:17:50 EST
References: <4224@topaz.RUTGERS.EDU>
Reply-To: ksbooth@watcgl.UUCP (Kelly Booth)
Organization: U of Waterloo, Ontario
Lines: 9
Summary: 

The classic algorithm is due to Bob Floyd.  It computes the transpose of
a matrix in something like n log n time (where n is the number of entries
in the matrix).  This will handle the case of 90 degrees.  The other angles
can be derived.  The basic unit of operation is "shuffling" the entries in
two "blocks" of the matrix (a page, a word, whatever) to produce two new
blocks consisting of exactly the entries from the original two, but permuted.

I don't have a direct reference at hand, but will look for one.  The algorithm
is from the 60's?