Re: std in NDArrays

[Jonathan Stickel]

Great, that's what I expected.  Since they are m-files, I see the cvs 
versions can be downloaded and put in my octave path:

http://www.octave.org/cgi-bin/viewcvs.cgi/*checkout*/octave/scripts/statistics/base/std.m
http://www.octave.org/cgi-bin/viewcvs.cgi/*checkout*/octave/scripts/general/repmat.m

Now I can do:

octave:13> A=rand(2,2,2)
A =

ans(:,:,1) =

     0.26272     0.39118
     0.60306     0.94343

ans(:,:,2) =

     0.51463    0.080546
     0.28459     0.46533

octave:14> std(A,0,3)

ans =

     0.17813     0.21965
     0.22519     0.33807

Does this work for you Hugo?

Jonathan


David Bateman wrote:
> repmat and std in the octave CVS have both been converted to work with
> NDArrays..... John, can we have a release?
>
> D.
>
> According to Jonathan Stickel <address@hidden> (on 08/25/04):
>
> > I was going to suggest the use of nanstd in the latest octave-forge:
> >
> >
> > octave:13> help nanstd
> > nanstd is the user-defined function from the file
> > /usr/share/octave/2.1.57/site/m/octave-forge/statistics/nanstd.m
> >
> > v = nanstd(X [, opt [, dim]]);
> > nanstd is identical to the std function except that NaN values are
> > ignored.  If all values are NaN, the std is returned as NaN. If there
> > is only a single non-NaN value, the std is returned as 0.
> >
> >        0:  normalizes with N-1 [default]
> >                provides the square root of best unbiased estimator of 
> > the variance
> >        1:  normalizes with N,
> >                this provides the square root of the second moment 
> > around the mean
> >
> > See also: nanmin, nanmax, nansum, nanmedian, nanmean
> >
> >
> > However, I get an error that repmat can only make 2D matrices.  Is there 
> > an update to repmat that will soon be available?
> >
> > Jonathan
> >
> >
> > Hugo Neto wrote:
> >
> > > Dear All,
> > >
> > > I'm facing another problem with the std (Standard Deviation) function. 
> > > Because i have a three dimensional array and i would like to do a std in 
> > > it along the 3º dimension.
> > >
> > > For instance in Matlab:
> > >
> > > realstate=std(state,0,3);        % std deviation along dimension 3
> > >
> > > This will store in realstate variable the standard deviation on the 3º 
> > > dimension
> > >
> > > In Octave i reach the following statement:
> > >
> > > "error: invalid conversion of NDArray to Matrix"
> > >
> > > I guess that this function is not yet implemented with NDArray option 
> > > in 2.1.57 Octave version. Do you know that?
> > >
> > > Any solution to surpass this problem?
> > >
> > > Thanks a lot,
> > >
> > > Regards,
> > >
> > > H.Neto
> >
> >
> >
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