code: public static Complex_F64 innerProd(ZMatrixRMaj x, ZMatrixRMaj y , Complex_F64 output )
      {
          if( output == null )
              output = new Complex_F64();
          else {
              output.real = output.imaginary = 0;
          }
  
          int m = x.getDataLength();
  
          for( int i = 0; i < m; i += 2 ) {
              double realX = x.data[i];
              double imagX = x.data[i+1];
  
              double realY = y.data[i];
              double imagY = y.data[i+1];
  
              output.real += realX*realY - imagX*imagY;
              output.imaginary += realX*imagY + imagX*realY;
          }
  
          return output;
      }
docs: <p>
  Computes the inner product of the two vectors.  In geometry this is known as the dot product.<br>
  <br>
  &sum;<sub>k=1:n</sub> x<sub>k</sub> * y<sub>k</sub><br>
  where x and y are vectors with n elements.
  </p>
  
  <p>
  These functions are often used inside of highly optimized code and therefor sanity checks are
  kept to a minimum.  It is not recommended that any of these functions be used directly.
  </p>
  
  @param x A vector with n elements. Not modified.
  @param y A vector with n elements. Not modified.
  @return The inner product of the two vectors.