Re: Index expressions, boolean types and numerical types

[Heber Farnsworth]

That's because k=y<11 is a boolean.  When you type y(k) it returns the 
corresponding element of y if k is "true" for that element.  But 
y(ones(1,10)) returns a vector of size 10x1 all of whose elements are 
the 1st element of y.

Heber

On Friday, October 24, 2003, at 03:30 PM, Greg Novak wrote:

> Does Octave have boolean types?  Does it keep track of them silently?  
> How
> do you do casts between numerical types and boolean types?  If there 
> are
> no boolean types, then how does the following fragment of a session 
> make
> sense?
>
> octave:68> y=1:10
> y = 1   2   3   4   5   6   7   8   9  10
> octave:69> y(y<11)
> ans = 1   2   3   4   5   6   7   8   9  10
> octave:70> k=y<11
> k = 1  1  1  1  1  1  1  1  1  1
> octave:71> y(k)
> ans = 1   2   3   4   5   6   7   8   9  10
> octave:72> k=ones(1,10)
> k = 1  1  1  1  1  1  1  1  1  1
> octave:73> y(k)
> ans = 1  1  1  1  1  1  1  1  1  1
> octave:74>
>
> k looks exactly the same when I assign it by k=y<11 or k=ones(1,10), 
> but
> the behavior of y(k) is very different in the two cases.
>
> What gives?
> Thanks,
> Greg
>
>
>
> -------------------------------------------------------------
> Octave is freely available under the terms of the GNU GPL.
>
> Octave's home on the web:  http://www.octave.org
> How to fund new projects:  http://www.octave.org/funding.html
> Subscription information:  http://www.octave.org/archive.html
> -------------------------------------------------------------



-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
-------------------------------------------------------------