You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: admStructDiff.m
    path of file: ./repos/d2d/arFramework3/ThirdParty/StrucID/adimat/runtime
    
    the code of the file until where you have to start completion: % function diffStr = admStructDiff(s1,s2)
%
%  Compare two structs and return a struct with differing fields from
%  s2.
%
% see also admOptions, admCompareOption
    
function diffStr = admStructDiff(s1,s2)
%
%  Compare two structs and return a struct with differing fields from
%  s2.
%
% see also admOptions, admCompareOptions
%
% This file is part of the ADiMat runtime environment.
%
% Copyright 2011 Johannes Willkomm, Institute for Scientific Computing   
%                     RWTH Aachen University
%
function diffStr = admStructDiff(s1,s2)

diffStr = struct();
fns = fieldnames(s2);

for i=1:length(fns)
  fns2 = fns{i};
  v2 = s2.(fns2);
  if ~isfield(s1, fns2)
    diffStr.(fns2) = v2;
  else
    v1 = s1.(fns2);
    if ~isequal(v1, v2)
      if isstruct(v1)
        diffStr.(fns2) = admStructDiff(v1, v2);
      else
        diffStr.(fns2) = v2;
      end