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Re: Preserving signbit for range operator
From: |
Daniel J Sebald |
Subject: |
Re: Preserving signbit for range operator |
Date: |
Mon, 25 Feb 2013 14:37:50 -0600 |
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On 02/25/2013 02:17 PM, Michael D. Godfrey wrote:
On 02/25/2013 03:03 PM, Daniel J Sebald wrote:
[-3:-0] -> [-3 -2 -1 0]
[-0:3] -> [-0 1 2 3]
This is at least "controversial." Sorts treat -0 and 0 as equal, but
they have to be recognized as different for various purposes such
as getting the directions right for functions of complex variables.
The complex number field is not an ordered field. What does direction mean?
So, it seems clear to me that the "right" result for the first line
above is: [-3:-0] -> [-3 -2 -1 -0].
I cannot think of an argument for not doing this.
Well, the definition of range needs to be tweaked then. To me the
current definition reads something analogous to [a:z:b] translates to
a a+1z a+2z ... a+Lz
where L is the largest integer for which a+Lz <= b. However,
technically that is not correct. It is not the maximum, necessarily,
but "maximum or minimum (whichever is pertinent based upon the order of
the limits a and b)". Consider:
octave:6> [0:-3:-5]
ans =
0 -3
No matter the choice, the description for the range could use some
mathematical accuracy.
Dan
PS: A bit arbitrary, but this result
- Preserving signbit for range operator, Rik, 2013/02/25
- Re: Preserving signbit for range operator, Michael D. Godfrey, 2013/02/25
- Re: Preserving signbit for range operator, Daniel J Sebald, 2013/02/25
- Re: Preserving signbit for range operator, Michael D. Godfrey, 2013/02/25
- Message not available
- Re: Preserving signbit for range operator, Daniel J Sebald, 2013/02/25
- Re: Preserving signbit for range operator, Michael D. Godfrey, 2013/02/25
- Re: Preserving signbit for range operator, Daniel J Sebald, 2013/02/25
- Re: Preserving signbit for range operator, Daniel J Sebald, 2013/02/27
- Re: Preserving signbit for range operator, Rik, 2013/02/27
- Re: Preserving signbit for range operator, Daniel J Sebald, 2013/02/27
- Re: Preserving signbit for range operator, Rik, 2013/02/27
- Re: Preserving signbit for range operator, Daniel J Sebald, 2013/02/27