Re: how can I return nothing?

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 vector however has direction, which we typically describe by an angle, which is not a binary concept (like +- sign).

IMO, your "sign of z", is useless redundant information, and has no importance in more abstract cases.


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.


An analogy for a program, would be to put a function in the stdlib, where only R.H. on Earth, wanted/needed to call this function!! :)


[1] http://www.diva-portal.org/ntnu/abstract.xsql?dbid=1257

--
Tor <torust [at] online [dot] no>
.

Relevant Pages

  • Re: GR Mathematical help request
    ... By radial curvature, I mean the amount of deformation of the ... Without a mass, the coordinate system would be rectilinear. ... So rc is a scalar expressed in meters. ...
    (sci.physics.relativity)
  • Re: C++ library for numerical computing
    ... However, to my surprise, ... or any other language, for that matter, ... The C++ Scalar, Vector, Matrix and Tensor class Library ...
    (comp.lang.cpp)
  • Re: massless or massive photon?
    ... which coordinate system is used. ... So convert it to tau, ... Integral gamma L d tau ... must be a Lorentz scalar. ...
    (sci.physics.relativity)
  • Re: Frequency and invariance, some trivialities.
    ... A scalar, a physical quantity that has the same value under ... any coordinate system. ...
    (sci.physics.relativity)
  • Re: help with one liners
    ... Michael Kelly - PCD ~ wrote: ... It does not work no matter what. ... Because your substitution operation is ... bound to the default scalar value $_, ...
    (comp.lang.perl.misc)