opdim(SIZ,DIM);

function DIM = opdim(SIZ,DIM);
% OPDIM Operating dimension.
%   DIM = OPDIM(SIZ) or OPDIM(SIZ,[]) is the first non singleton dim-
%   ension in the N-D array of size SIZ.
%
%   DIM = OPDIM(SIZ,DIM) is the dimension DIM in an N-D array of size
%   SIZ, if the dimension is valid. If the dimension is unvalid or is
%   set to the default dimension DIM = [] the first non singleton dim-
%   ension along the N-D array of size SIZ is returned.
%
%   See also NDOP.
%
% @author   Ingo Lhken, [e-mail]
% @rev      26/10/2005
% @toolbox  DIMEXP, ver 0.1
try;
    error(nargchk(1,2,nargin));
    error(nargoutchk(0,1,nargout));
    
    if ndims(SIZ) > 2 || ~isnumeric(SIZ) || ~any(size(SIZ) <= 1);
        error('~isvector(SIZ)');
    elseif any(floor(SIZ) ~= SIZ);
        error('~isnat(SIZ)');
    end;
    
    % Translate Operating Dimension
    if nargin < 2 || isempty(DIM);
        S = find(SIZ > 1);
        
        if isempty(S);
            DIM = 1;
        else;
            DIM = S(1);
        end;
    else;
        try;
            if ndims(DIM) > 2 || any(size(DIM) ~= 1) || ~isnumeric(DIM);
                error('~isscalar(DIM)');
            elseif DIM <= 0;
                error('DIM <= 0');
            elseif DIM > length(SIZ);
                error('DIM > length(SIZ)');
            end;
        catch;
            evalin('caller','warning(''Operating dimension DIM is out dimensions and set to first operating one.'')');
            DIM = opdim(SIZ,[]);
        end;
    end;    
catch;
    error([mfilename,': ',lasterr]);
end;