Re: how can I return nothing?

Tor Rustad said:

Richard Heathfield wrote:
<snip>

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.

I think you picture a single real axis.

Indeed. A straightforward real axis <--- thisaway ---> and an imaginary
axis at right angles to it. That's the complex arithmetic I'm discussing.

In theoretical physics (e.g. special relativity), we rather use 3 such
axis (x, y and z), as well as an imaginary axis for time.

If you want to talk about that, that's fine, but that's not what I'm
talking about.

<snip>

Now, please name a mathematician who think that your "sign of z":

Not mine. AFAICR I haven't even mentioned a "sign of z".

sign(z) = Re(z) / |Re(z)|

What happened to the sign of the imaginary component?

--
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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