code: public static double innerProd(DMatrixD1 x, DMatrixD1 y )
      {
          int m = x.getNumElements();
  
          double total = 0;
          for( int i = 0; i < m; i++ ) {
              total += x.get(i) * y.get(i);
          }
  
          return total;
      }
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.