Re: how can I return nothing?

Tor Rustad said:

Richard Heathfield wrote:
Tor Rustad said:

Richard Heathfield wrote:

[...]

but I cannot accept that there is no such thing as a non-negative
*complex* number.

Just view a complex number as a vector, the useful properties of a
vector is the direction and magnitude. Those properties fully describe
it in a N-dimensional case too, no matter what coordinate system you
use.

You could use the same argument for real numbers.

No you can't, a scalar is a scalar.

A real number is a point on the real number line. A complex number is a
point on the complex plane. If you can call one a vector, you can call the
other a vector too. A real number is a special case of a complex number,
so if a complex number is a vector, so is a real number.

Why is useful to define a sign of z as the projection along the Re
axis?

Ask any mathematician if they'd rather do without the concept of sign.

OK, I just did, the answer from my brother [1] was why introduce a
definition there is little use of?! He added, in his latest referee
report, he had criticized the author for using too many definitions.

So your brother is prepared to eschew negative numbers? Fine - that makes
him a number theorist - but not all mathematicians restrict themselves to
number theory.

--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999
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