//-------------------------------------------------------------------------
public virtual void test_plus()
{
DoubleMatrix test1 = DoubleMatrix.of(2, 3, 1d, 2d, 3d, 4d, 5d, 6d);
DoubleMatrix test2 = DoubleMatrix.of(2, 3, 0.5d, 0.6d, 0.7d, 0.5d, 0.6d, 0.7d);
assertMatrix(test1.plus(test2), 1.5d, 2.6d, 3.7d, 4.5d, 5.6d, 6.7d);
assertThrows(() => test1.plus(DoubleMatrix.EMPTY), typeof(System.ArgumentException));
}