docs: public static double innerProdA(DMatrixD1 x, DMatrixD1 A , DMatrixD1 y )
      {
          int n = A.numRows;
          int m = A.numCols;
  
          if( x.getNumElements() != n )
              throw new IllegalArgumentException("Unexpected number of elements in x");
          if( y.getNumElements() != m )
              throw new IllegalArgumentException("Unexpected number of elements in y");
  
          double result = 0;
  
          for( int i = 0; i < m; i++ ) {
              double total = 0;
  
              for( int j = 0; j < n; j++ ) {
                  total += x.get(j)*A.unsafe_get(j,i);
              }
  
              result += total*y.get(i);
          }
  
          return result;
      }