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Path: utzoo!linus!philabs!cmcl2!seismo!brl-tgr!gwyn
From: gwyn@brl-tgr.ARPA (Doug Gwyn )
Newsgroups: net.graphics
Subject: Re: Dithering and a project
Message-ID: <5404@brl-tgr.ARPA>
Date: Fri, 19-Oct-84 21:08:25 EDT
Article-I.D.: brl-tgr.5404
Posted: Fri Oct 19 21:08:25 1984
Date-Received: Sat, 20-Oct-84 07:37:57 EDT
References: <1556@ucla-cs.ARPA> <16648@arizona.UUCP>
Organization: Ballistic Research Lab
Lines: 10

> I need a quick way to determine the solution for z of
> 	A*z^2 + B*z*x + C*z + D*x^2 + E*x + F >= 0
> at (x+1), given the solution at x.  "Quick" means faster than substituting
> the new x value and solving directly.

(You must mean = 0, not >= 0.)
Sorry, Roger, after cleaning up the statement of the problem,
I find that you must solve a quadratic equation no matter what.
The best you can do is to take some shortcuts in evaluating the
coefficients of the quadratic.