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Re: Easy about Matrices
From: |
Peter Bodin |
Subject: |
Re: Easy about Matrices |
Date: |
Tue, 19 Apr 2005 11:17:21 +0200 (CEST) |
User-agent: |
SquirrelMail/1.4.4-2 |
> Frank Palazzolo wrote:
>
>>This syntax works as well:
>>
>>x = randn(1,1000);
>>x_positive = (x>=0);
>>x_negative = (x<0);
>>
>>I'm not sure if it's any more efficient, but it seems it would be,
>> since it
>>never needs to build an explicit index vector.
>>
>>-Frank
>>
>>
> This is definitely faster, but it doesn't return the same matrix:
>
> octave:1> x=randn(1,10);
> octave:1> (x>0)
> ans =
>
> Columns 1 through 8:
> 1 1 0 0 0 0 1
> 0
> Columns 9 and 10:
> 1 1
>
> octave:3> x(find(x>0))
> ans =
>
> 0.93970 0.38451 0.30387 0.81479 2.46831
>
>
>
>
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>
>
Hi!
Why not use logical indexing?
x(x>0)
or am I missing the obvoius here?
/PB
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