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[Octave-bug-tracker] [bug #40813] atan2 returns no results for sparse ma
From: |
Stefan Mahr |
Subject: |
[Octave-bug-tracker] [bug #40813] atan2 returns no results for sparse matrices |
Date: |
Mon, 20 Jan 2014 16:54:57 +0000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/31.0.1650.63 Chrome/31.0.1650.63 Safari/537.36 |
Follow-up Comment #1, bug #40813 (project octave):
Attached a possible fix. Don't know if 'copy_or_memcopy' is ok here, but seems
the be the fastest solution.
One option would be to copy the whole sparse matrix using existing method, but
then data is copied for nothing. Other possibility is to rewrite column and
row index within for loop, but this is slow. Third option: Create new method?
Also, MATLABs behaviour differs a little bit. This is also fixed with the
attached patch.
This is the MATLAB result:
>> x=sparse([1 2]);
>> atan2(x,x)
ans =
(1,1) 0.785398163397448
(1,2) 0.785398163397448
>> atan2(x,2)
ans =
(1,1) 0.463647609000806
(1,2) 0.785398163397448
>> atan2(x,[1 2])
ans =
(1,1) 0.785398163397448
(1,2) 0.785398163397448
>>
>> atan2(2,x)
ans =
1.10714871779409 0.785398163397448
>> atan2([1 2],x)
ans =
0.785398163397448 0.785398163397448
(file #30320)
_______________________________________________________
Additional Item Attachment:
File name: atan2_spare.patch Size:1 KB
_______________________________________________________
Reply to this item at:
<http://savannah.gnu.org/bugs/?40813>
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- [Octave-bug-tracker] [bug #40813] atan2 returns no results for sparse matrices,
Stefan Mahr <=