anchor.diff:  
   Now we have all pieces ready, here is our function for general 4x4 matrix inverse:
   
  -[source, C/C++]
  +[source,C++]
   ----
   // Inverse function is the same no matter column major or row major
   // this version treats it as row major
  
positive.code: 
  Before we jump in intrinsics, I would like to define a bunch of shuffle/swizzle macros. Hopefully they will make it easier to read. We also make use of faster instructions for special shuffles.
  
  [source, C/C++]
  ----
  #define MakeShuffleMask(x,y,z,w)			(x | (y<<2) | (z<<4) | (w<<6))
  
  
negative.code: 
  Here’s the code for these three functions:
  
  [source,C++]
  ----
  // for row major matrix
  // we use __m128 to represent 2x2 matrix as A = | A0  A1 |
  