Re: Easy about Matrices

[Quentin Spencer]

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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