On 2015-03-01 22:44, rcs@xmission.com wrote:
i is for the POSITIVE square root of -1. :-)
Macsyma: Is %I positive, negative, or zero? me: no Macsyma: Is %I positive, negative, or zero? me: no ... Jeff Golden: It's positive. Everybody knows that. --rwg
----- Quoting Dan Asimov <dasimov@earthlink.net>:
What bothers me is the unqualified use of sqrt(-1) to mean i, since I think that should always be described as a convention.
Sometimes it seems to me we have no right to use a symbol for i, just because there is no way to distinguish between i and -i. Maybe we should be allowed only to refer to both of them at once.
--Dan
On Mar 1, 2015, at 5:57 PM, Adam P. Goucher <apgoucher@gmx.com> wrote:
Using j as a square-root of -1 never bothered me, since you can use *any* purely-imaginary unit quaternion and (as long as you're consistent) you get a copy of the complex plane.
Amusingly, working in the quaternions, complex conjugation is a special case of the other type of conjugation:
(a + bi) = j (a - bi) j^-1
Sincerely,
Adam P. Goucher
Sent: Monday, March 02, 2015 at 1:44 AM From: meekerdb <meekerdb@verizon.net> To: "Eugene Salamin" <gene_salamin@yahoo.com>, math-fun <math-fun@mailman.xmission.com> Subject: Re: [math-fun] ln
On 3/1/2015 5:17 PM, Eugene Salamin via math-fun wrote:
In a book on pure mathematics, "log" could not reasonably mean anything other than natural logarithm; there should be no confusion about such usage. In a subject such as chemistry or astronomy, natural and common logarithms both appear, and it makes sense to use both "log" and "ln" to distinguish them. What absolutely irritates me is the use of j for ?-1. That comes from electrical engineering practice. They liked j because they were already using i for current.
Brent
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