octave 3.2.0 parser

[Alexander Barth]

On Tue, Jun 9, 2009 at 12:18 AM, John W. Eaton<jwe at octave.org> wrote:
> On  8-Jun-2009, Alexander Barth wrote:
>
> | On Mon, Jun 8, 2009 at 8:24 PM, John W. Eaton<jwe at octave.org> wrote:
> | > On  8-Jun-2009, Alexander Barth wrote:
> | >
> | > | The matlab netcdf toolbox in octave uses expressions like these:
> | > |
> | > |  f{'myVariable', 1}(i, j, ...) = myVariableData
> | > | (see http://ecco2.jpl.nasa.gov/data1/matlab/netcdf_toolbox/netcdf/@netcdf/netcdf.m).
> | > |
> | > | With octcdf I implemented this functionality in octave. However since
> | > | octave 3.2.0, such expressions trigger an error:
> | > |
> | > | octave:1>  nc{'autoscale_var',1}(:) = var;
> | > | error: a cs-list cannot be further indexed
> | > | error: evaluating argument list element number 1
> | > |
> | > | It worked previously in octave 3.0.5.
> | >
> | > What are the values of the variables NC and VAR?
> | >
> | > jwe
> | >
> |
> | nc is ncfile. This object is created in octcdf
> | (http://octave.svn.sourceforge.net/viewvc/octave/trunk/octave-forge/main/octcdf/src/ov-ncfile.h?revision=4812&view=markup)
> | and var is just a matrix. A complete example (which requires octcdf)
> | would be:
> |
> | nc = netcdf('test.nc','c'); % creates a netcdf file test.nc
> |
> | nc('time') = 5;  % defines dimension time
> | nc('space') = 3; % defines dimension space
> |
> | var = rand(5,3);
> |
> | nc{'autoscale_var'} =  ncdouble('time','space');  % defines a variable
> | depending on time and space
> | nc{'autoscale_var'}.add_offset = 1; % variable will be stored with an
> | offset of 1
> | nc{'autoscale_var'}.scale_factor = .1; % and scaled by a factor of .1
> | nc{'autoscale_var',1}(:) = var; % write variable to netcdf file with
> | autoscaling enabled
> |
> | close(nc) % close netcdf file
> |
> | I have this problem with octave 3.2.0 compiled with --enable-64, but I
> | don't think that this option has something to do with this (or not?)
>
> I don't understand precisely what it is you are trying to do, but
> apparently in your expression
>
>  nc{'autoscale_var',1}(:) = var;
>
> the first part
>
>  nc{'autoscale_var',1}
>
> is creating a comma-separated list, and you can't index a
> comma-separated list now.  A comma-separated list is just a group of
> objects, not a single object.  So indexing it doesn't make sense.
>
> jwe
>

I'm trying to be more clear what this expression is doing.
The first part "nc{'autoscale_var',1}" is creating a new object (a
netcdf variable) by calling the method subsagn of the netcdf file.
'autoscale_var' and 1 are passed to subsagn by the parameter idx. The
resulting netcdf variable is then indexed with (:).

I realize than those expressions seem to be quite "baroque", but I
needed to implement them in octcdf to be compatible with the matlab
netcdf toolbox (and those expressions are valid in matlab).

If one separates the assignment in different steps, it actually works
in octave 3.2.0:
nv = nc{'autoscale_var',1};
nv(:) = var;

Thanks and regards
Alex