Date: Mon, 19 May 2008 18:28:49 +0100 (BST) From: Jan Grant <jan.grant@bristol.ac.uk> To: Greg 'groggy' Lehey <grog@FreeBSD.org> Cc: Jim Capozzoli <saltmiser@gmail.com>, freebsd-chat@freebsd.org Subject: Re: slide rules Message-ID: <20080519182201.N68739@tribble.ilrt.bris.ac.uk> In-Reply-To: <20080519035209.GT46655@dereel.lemis.com> References: <37f72b1f0805181418j16efd60fge243160dbfdc6789@mail.gmail.com> <20080519035209.GT46655@dereel.lemis.com>
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On Mon, 19 May 2008, Greg 'groggy' Lehey wrote: > On Sunday, 18 May 2008 at 17:18:30 -0400, Jim Capozzoli wrote: > > I was > > considering figuring out how to do Trig on it and then taking my Trig > > final with it. :) [snip] > To multiply two numbers, you place the 1 on the C scale (bottom of the > slide) against the first number on the D scale (directly below on the > body). Move the cursor (or your eye :-) to the second number on the C > scale, and read off the result on the D scale. This follows naturally from: ln (xy) = ln x + ln y If you're trying to do trig, presumably the same ideas apply. Since cos x = 1/2 (e^ix + e^-ix) you need to be able to move one half of the slide rule perpendicular to the plane that the other half occupies? Yours in theory, jan -- jan grant, ISYS, University of Bristol. http://www.bris.ac.uk/ Tel +44 (0)117 3317661 http://ioctl.org/jan/ They modified their trousers secretly.
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