[X]=submat(X,varargin)

function [X]=submat(X,varargin)
%SUBMAT    Returns a submatrix reduced along indicated dimensions
%
%    Description: Y=SUBMAT(X,DIM,LIST) creates a matrix Y that is the
%     matrix X reduced along dimension DIM to the indices in LIST.  If DIM
%     is a list of dimensions, LIST is used to reduce each dimension.  LIST
%     also may be any string that can be evaluated to valid indices along 
%     DIM such as '1:end-1', '[2 4]', 'X(2,:)', and 'some_other_function'.
%     DIM can not be a string!
%
%     Y=SUBMAT(X,DIM1,LIST1,DIM2,LIST2,...) allows for access to multiple
%     dimensions independently.
%
%    Usage: Y=submat(X,DIM1,LIST1,DIM2,LIST2,...)
%
%    Examples:
%      Return x reduced to only the elements in index 1 of dimension 5:
%      x=submat(x,5,1)
%
%      Remove the last elements along dimensions 2 and 3 of x:
%      x=submat(x,[2 3],'1:end-1')
%
%      These are equivalent:
%      x=repmat(x,[1 2 ones(1,ndims(x)-2)])
%      x=submat(x,2,'1:end 1:end')
%
%    See also: eval, colon operator (:), end, repmat

% CHECK VARARGIN
if(~mod(nargin,2))
    error('dimension argument must be followed by indices argument');
end

% DEFAULT TO ENTIRE MATRIX AND EXPAND TO MAX INPUT DIMENSION
[list{1:max([ndims(X) [varargin{1:2:end}]])}]=deal('1:end');

% REDUCTION/REPLICATION OF DIMENSIONS
for i=1:2:nargin-2
    if(ischar(varargin{i+1}))
        [list{[varargin{i}]}]=deal(varargin{i+1});
    else
        [list{[varargin{i}]}]=deal(mat2str(varargin{i+1}));
    end
end

% FORM STRING FOR EVAL
list(1)=strcat('X(',list(1));               % ADD FRONT
list(1:end-1)=strcat(list(1:end-1),',');    % ADD COMMAS
list(end)=strcat(list(end),')');            % ADD REAR
string=strcat(list{:});                     % COMBINE
clear list varargin i                       % CLEAN UP

% EVAL
X=eval(string);

end