function varargout=scalardistribute(varargin)
%SCALARDISTRIBUTE  Copy scalar to array shape for parameter handling
%   Usage:  [...] = scalardistribute(...);
%
%   [...]=SCALARDISTRIBUTE(...) copies the input parameters to the
%   output parameters.
%
%    If one of the input parameters is an array, all the output parameters
%     will be column vectors containing the same number of elements. If one
%     of the other input parameters is a scalar, it will be replicated to
%     the correct length. This allows a scalar value to be repeated for
%     all conditions.
%
%    If two or more input parameters are arrays, the must have the exact
%     same size. They will be converted to vectors and returned in the
%     output parameters. This allows two arrays to co-vary at the same time.
%
%   This operator is usefull for sanitizing input parameters: The user is
%   allowed to enter scalars or arrays as input paremeters. These input
%   are in turn passed to SCALARDISTRIBUTE, which makes sure that the
%   arrays have the same shape, and that scalars are replicated. The user
%   of scalardistibute can now generate conditions based on all the
%   parameters, and be sure the have the right sizes.
%
%   As an example, consider:
%
%     [a,b,c]=scalardistribute(1,[2,3],[4,5])
%
%
%   Url: http://ltfat.github.io/doc/scalardistribute.html

% Copyright (C) 2005-2015 Peter L. Soendergaard <peter@sonderport.dk>.
% This file is part of LTFAT version 2.1.1
%
% This program is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program.  If not, see <http://www.gnu.org/licenses/>.
  
  npars=length(varargin);
  
  scalartest=zeros(npars,1);
  for ii=1:npars
    if ~isnumeric(varargin{ii})
      error('%s: Input no. %i must be numerical.',upper(mfilename),ii);
    end;
    if isempty(varargin{ii})
      error('%s: Input no. %i is empty.',upper(mfilename),ii);
    end;

    scalartest(ii)=isscalar(varargin{ii});
  end;

  idx=find(scalartest==0);
  
  % Tjeck that all non-scalars have the same shape
  for jj=1:numel(idx)
    ref_size  = size(varargin{idx(1)});
    this_size = size(varargin{idx(jj)});
    if any((ref_size-this_size)~=0)
      error('%s: Input no. %i and no. %i must have the same shape.',upper(mfilename),idx(1),idx(jj));
    end;
  end;  

  if numel(idx)==0
    % All arguments are scalar, so this is just a dummy, but it must
    % still be defined for the code not to fail.
    shape=1;
  else
    shape=ones(numel(varargin{idx(1)}),1);
  end;
  
  varargout=cell(1,npars);
  for ii=1:npars
    if scalartest(ii)
      % Replicate scalar
      varargout{ii}=shape*varargin{ii};
    else
      % Copy input and turn it into a vector. This would be a one-liner
      % in Octave.
      tmp=varargin{ii};
      varargout{ii}=tmp(:);
    end;
  end;
  
  

