slide rules

[Jan Grant]

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.