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[Octave-bug-tracker] [bug #51657] gausswin produces slightly wrong resul
From: |
Nicholas Jankowski |
Subject: |
[Octave-bug-tracker] [bug #51657] gausswin produces slightly wrong result |
Date: |
Fri, 11 Aug 2017 16:27:18 -0400 (EDT) |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0 |
Follow-up Comment #3, bug #51657 (project octave):
Ok, the last one is just weird. Matlab documentation mentions that N (M in
the octave version) must be a positive integer. So the warning and rounding
is not unexpected. but the fact that it accepts an array is odd, and odd
results come about:
>> gausswin(1)
ans =
1
>> gausswin([1 1 1 1 1])
ans =
1
>> gausswin([1 1 2 1 1])
ans =
0.043936933623407
>> gausswin([1 1 2 1 1]')
ans =
Columns 1 through 3
1.000000000000000 1.000000000000000 1.000000000000000
1.000000000000000 1.000000000000000 1.000000000000000
1.000000000000000 1.000000000000000 0.043936933623407
1.000000000000000 1.000000000000000 1.000000000000000
1.000000000000000 1.000000000000000 1.000000000000000
Columns 4 through 5
1.000000000000000 1.000000000000000
1.000000000000000 1.000000000000000
1.000000000000000 1.000000000000000
1.000000000000000 1.000000000000000
1.000000000000000 1.000000000000000
best as I can guess from the formula on the help page is that there's a matrix
multiplication or division that is allowed to occur
>> a = [1 1 2 1 1];
>> a/a
ans =
1.000000000000000
>> a'/a'
ans =
Columns 1 through 3
0 0 0.500000000000000
0 0 0.500000000000000
0 0 1.000000000000000
0 0 0.500000000000000
0 0 0.500000000000000
Columns 4 through 5
0 0
0 0
0 0
0 0
0 0
I don't think that is at all intended. and it's not documented. So I'm going
to ignore it and leave it as an error in octave for now unless matlab
documentation changes.
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