Re: More DLD mysteries

[Al Niessner]

Sorry it took so long, but I am just getting back to this. So, if Matrix
is two dimensional and any() and all() reduce the order by one, then why
do they return a Matrix? ColumnVector and RowVector are the one
dimensional counterparts. I would then think that ColumnVector any() or
all() would reduce to a scalar (boolean actually). However, there is no
any() or all() for {Column,Row}Vector.  So, I have to do something like:

ColumnVector c;

...
c = ...;
if ((Matrix(c) < SomeDelta).bool_matrix_value().any()(0,0))
{
   ...do something significant maybe...
}

The point here being I have no idea if the conditional in the C++ if
statement is the same as my m-file of 'if (any(c < SomeDelta))'. There
is nothing in any header file in the include/octave... directory that
helps to clear it up. It does compile, so we will see.

Thanks for the help.

On Tue, 2004-03-09 at 17:09, JD Cole wrote:
> Al,
>     At first glance, it looks like an argument gets passed to 'any' or 
> 'all', if you don't want to specify a dimension, pass -1 (see 
> src/data.cc ANY_ALL macro). They both also reduce the dimensionality by 
> one, similar to when we do max(max(some_2d_matrix)), so if your mattrix 
> is 2d, use any/all twice and then use then index the "top-left" item of 
> the bools matrix returned.
> 
> Hope this helps,
> 
> JD
> 
> Al Niessner wrote:
> 
> >I am now looking for all() and any(). I have the expression "if any (a <
> >b)" and "if all (b < a)" type of thing in my m-file. I cannot find an
> >equivalent function that reduces to a boolean in the header files. I
> >tried "if (boolMatrix(a < b).any()) but that fails at compilation
> >because it returns yet another matrix and not a boolean. Any suggestions
> >are welcome and thanks in advance.
> > 
> >  
> >
-- 
Al Niessner <address@hidden>
Jet Propulsion Laboratory

All opinions stated above are mine and do not necessarily reflect 
those of JPL or NASA.

 ----
| dS | >= 0
 ----



-------------------------------------------------------------
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
-------------------------------------------------------------