time   calls  line
                  1 function s = setfield(s,varargin)
                  2 %SETFIELD Set structure field contents.
                  3 %   S = SETFIELD(S,'field',V) sets the contents of the specified
                  4 %   field to the value V.  This is equivalent to the syntax S.field = V.
                  5 %   S must be a 1-by-1 structure.  The changed structure is returned.
                  6 %
                  7 %   S = SETFIELD(S,{i,j},'field',{k},V) is equivalent to the syntax
                  8 %       S(i,j).field(k) = V;
                  9 %
                 10 %   In other words, S = SETFIELD(S,sub1,sub2,...,V) sets the
                 11 %   contents of the structure S to V using the subscripts or field
                 12 %   references specified in sub1,sub2,etc.  Each set of subscripts in
                 13 %   parentheses must be enclosed in a cell array and passed to
                 14 %   SETFIELD as a separate input.  Field references are passed as
                 15 %   strings.  
                 16 %
                 17 %   For improved performance, when setting the value of a simple 
                 18 %   field, use <a href="matlab:helpview([docroot '/techdoc/matlab_prog/matlab_prog.map'], 'dynamic_field_names')">dynamic field names</a>.
                 19 %
                 20 %   See also GETFIELD, ISFIELD, FIELDNAMES, ORDERFIELDS, RMFIELD.
                 21  
                 22 %   Copyright 1984-2007 The MathWorks, Inc.
                 23 %   $Revision: 1.22.4.9 $  $Date: 2010/08/23 23:07:53 $
                 24 
                 25 % Check for sufficient inputs
  0.01      78   26 if (isempty(varargin) || length(varargin) < 2) 
                 27     error(message('MATLAB:setfield:InsufficientInputs'));
                 28 end
                 29 
                 30 % The most common case
            78   31 arglen = length(varargin); 
            78   32 strField = varargin{1}; 
            78   33 if (arglen==2) 
            78   34     s.(deblank(strField)) = varargin{end};     
            78   35     return 
                 36 end
                 37         
                 38 subs = varargin(1:end-1);
                 39 types = cell(1, arglen-1);
                 40 for i = 1:arglen-1
                 41     index = varargin{i};
                 42     if (isa(index, 'cell'))
                 43         types{i} = '()';
                 44     elseif ischar(index)        
                 45         types{i} = '.';
                 46         subs{i} = deblank(index); % deblank field name
                 47     else
                 48         error(message('MATLAB:setfield:InvalidType'));
                 49     end
                 50 end
                 51 
                 52 % Perform assignment
                 53 try
                 54    s = builtin('subsasgn', s, struct('type',types,'subs',subs), varargin{end});   
                 55 catch exception
                 56     exceptionToThrow = MException('MATLAB:setfield', '%s', exception.message);
                 57     throw(exceptionToThrow);
                 58 end

Other subfunctions in this file are not included in this listing.