public void Determ() { var A = MathS.Matrix(new Entity[, ] { { "A", "B" }, { "C", "D" } }); var v = TestExtensions.AsNotNull(A.Determinant) .Substitute("A", 1) .Substitute("B", 2) .Substitute("C", 3) .Substitute("D", 4); Assert.Equal(-2, v.EvalNumerical()); }