Subject: Re: voltage & current program
From: (Rob Warnock)
Date: Wed, 18 Apr 2007 03:34:03 -0500
Newsgroups: comp.lang.lisp
Message-ID: <>
Thomas A. Russ <> wrote:
| (Rob Warnock) writes:
| >   (defun resistor-ohm-law (&key v r i)
| >     (cond
| >       ((and v i r)
| >        (error "May not specify all three parameters!"))
| Actually, at this point, I would evaluate Ohm's law and only signal
| an error if it wasn't valid.

An iteresting idea, except that it violates one of the prime tenets
of dealing with floating-pont numbers, which is *never* to compare
them for exact equality!!  [And if you're not going to use "=", then
you would need an additional :EPSILON keyword to specify the acceptable
error in the comparison, and that's just getting ugly...]


Rob Warnock			<>
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