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\imath

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Andrew McCafferty

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Dec 20, 2002, 5:20:05 PM12/20/02
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I'm doing a dissertation on complex analysis, so understandably I need to
use the symbol i, for the square root of -1. Unfortunately, the version that
comes out when I use "\imath" lacks a dot on top! Anybody here know if
there's another "control sequence" I could use?
--
Andrew McCafferty
(www.lancs.ac.uk/~mccaffea)


José Carlos Santos

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Dec 20, 2002, 5:28:40 PM12/20/02
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Andrew McCafferty wrote:
> I'm doing a dissertation on complex analysis, so understandably I need to
> use the symbol i, for the square root of -1. Unfortunately, the version that
> comes out when I use "\imath" lacks a dot on top! Anybody here know if
> there's another "control sequence" I could use?

I write a lot on complex analysis and I simply use the letter i. What's
wrong with it?

Best regards

Jose Carlos Santos

Andrew McCafferty

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Dec 21, 2002, 11:35:16 AM12/21/02
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> I write a lot on complex analysis and I simply use the letter i. What's
> wrong with it?
>
> Best regards
>
> Jose Carlos Santos
>

All the textbooks and printed notes (at my university) have a kind of
italicised and rounded i, not the normal i.


Christian Justen

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Dec 21, 2002, 12:20:26 PM12/21/02
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Andrew McCafferty schrieb:

Well, if you use the letter i in math mode, it will be an italic one ...

Christian.

Julian V. Noble

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Jan 1, 2003, 8:02:55 PM1/1/03
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I usually just use i inside a mathematical expression. However, if I
want to indicate "i" as a very visible symbol (for example if I'm
defining it as a 2x2 matrix -- as I might define 1 as a 2x2 unit
matrix) I would set them as \mathbf{i} and \mathbf{1} .

--
Julian V. Noble
Professor of Physics
j...@virginia.edu

"Science knows only one commandment: contribute to science."
-- Bertolt Brecht, "Galileo".

Bo Thide'

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Jan 3, 2003, 2:22:57 AM1/3/03
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In good typography, the imaginary unit `i' in mathematical expressions
should be upright roman. This can be achieved by the definition (in
the preamble on in a style file)

\renewcommand*{\i}{{\mathrm{i}}}

and then by using `\i' in math expressions. Using `i' as is in math
expressions will result in an italic `i' which could be mistaken for
a running index and therefore should be avoided.

Regards,

Bo

--

Bo Thidé, Professor, Programme Director http://www.physics.irfu.se/~bt
Swedish Institute of Space Physics (IRFU), Box 537, SE-752 21 Uppsala
Office: Ångström Laboratory, Room 14144, Lägerhyddsvägen 1, Uppsala
Phone: 018-471 59 14 Fax: 018-471 59 05 Mobile Phone: 0705-61 36 70
Mathematics and Systems Engineering, Växjö University, SE-351 95 Växjö
E-Mail: b...@irfu.se, btmo...@irfu.se http://www.lois-space.org

Maurizio Loreti

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Jan 3, 2003, 3:52:35 AM1/3/03
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Bo Thide' <b...@see.irfu.se> writes:

> In good typography, the imaginary unit `i' in mathematical expressions
> should be upright roman. This can be achieved by the definition (in
> the preamble on in a style file)
>
> \renewcommand*{\i}{{\mathrm{i}}}
>
> and then by using `\i' in math expressions. Using `i' as is in math
> expressions will result in an italic `i' which could be mistaken for
> a running index and therefore should be avoided.

While I agree with the "good tipography" remark, I _strongly_ suggest
to avoid redefining such a basic TeX command as \i, being used to
sequences like \`\i in Italian. Also, I would use \ensuremath in the
definition body.

--
Maurizio Loreti http://www.pd.infn.it/~loreti/mlo.html
Dept. of Physics, Univ. of Padova, Italy ROT13: ybe...@cq.vasa.vg

Dan Luecking

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Jan 3, 2003, 3:02:25 PM1/3/03
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On 03 Jan 2003 09:52:35 +0100, Maurizio Loreti <mlo...@pd.infn.it>
wrote:

>Bo Thide' <b...@see.irfu.se> writes:
>
>> In good typography, the imaginary unit `i' in mathematical expressions
>> should be upright roman. This can be achieved by the definition (in
>> the preamble on in a style file)
>>
>> \renewcommand*{\i}{{\mathrm{i}}}
>>
>> and then by using `\i' in math expressions. Using `i' as is in math
>> expressions will result in an italic `i' which could be mistaken for
>> a running index and therefore should be avoided.
>
>While I agree with the "good tipography" remark, I _strongly_ suggest
>to avoid redefining such a basic TeX command as \i, being used to
>sequences like \`\i in Italian. Also, I would use \ensuremath in the
>definition body.

Good typography notwithstanding, the standard used by complex
analysts (who obviously use `i' quite a lot), is a normal
math italic i. It matches other symbols and variables, and it does
not stand out (which it shouldn't, it being just another number).

This is pretty much the same way we treat all numbers with a letter
for a name: $e^{i\pi} = -1$ looks right, bold or upright e's or i's
look wrong. Bold is normally reserved for vectors and other
composite objects, upright roman for operators and named functions
(d, sin, log, etc.).

And we never have any problem with `i' as a running index, because
we can use j, k, l, m, n, (and even p, q, etc., when necessary).


Dan (you can trust me, I'm a complex analyst)

--
Dan Luecking Department of Mathematical Sciences
University of Arkansas Fayetteville, Arkansas 72701

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