code: public static DoubleMatrix ger(double alpha, DoubleMatrix x,
  			DoubleMatrix y, DoubleMatrix a) {
  		NativeBlas.dger(a.rows, a.columns, alpha, x.data, 0, 1, y.data, 0, 1, a.data,
  				0, a.rows);
  		return a;
  	}
docs: Compute A <- alpha * x * y^T + A (general rank-1 update)