Re: Preserving signbit for range operator

[Daniel J Sebald]

On 02/25/2013 01:14 PM, Rik wrote:
> 2/25/13
>
> All,
>
> Michael Godfrey and I are working on the stemleaf.m code and we noticed
> that the range operator is not preserving the signbit on 0.
>
> As an example, [-3:-0] produces [-3 -2 -1 0] or [-0:3] which produces [0 1
> 2 3].
>
> First, should we be trying to preserve the signbit or is this just too much
> work for too little gain?

Maybe.  Here is the "definition" of the range operation in the DOC:

"A range expression is defined by the value of the first
element in the range, an optional value for the increment between
elements, and a maximum value which the elements of the range will not
exceed."

Note that the right most number is the *maximum* value not exceeding the 
right limit, e.g.,

octave:23> 1:3:5
ans =

   1   4

and not the end of range specification itself.  With that I would think 
that perhaps the following should be the results of your examples.

[-3:-0] -> [-3 -2 -1 0]
[-0:3] -> [-0 1 2 3]

Dan

PS:  There may be some broken links in the DOC, but I've never been good 
at navigating DOC, so I'll look at the source code later today.  In 
"doc" I navigate to

* Operator Index::              An item for each documented operator.

and hit return.  That takes me to the index of operators.  I then 
navigate to

* ::                                     Ranges.              (line   6)

and hit return.  That takes me to GNU Octave menu.  These two

* : <1>:                                 Operator Overloading.
                                                              (line  10)
* : <2>:                                 Index Expressions.   (line   6)

just jump down the page to

* <:                                     Comparison Ops.      (line  23)