from sympy import symbols, pi, sin, cos, Float, ImmutableMatrix as Matrix from sympy.physics.vector import ReferenceFrame, Vector, dynamicsymbols, dot from sympy.abc import x, y, z from sympy.testing.pytest import raises Vector.simp = True A = ReferenceFrame('A') def test_Vector(): assert A.x != A.y assert A.y != A.z assert A.z != A.x assert A.x + 0 == A.x v1 = x*A.x + y*A.y + z*A.z v2 = x**2*A.x + y**2*A.y + z**2*A.z v3 = v1 + v2 v4 = v1 - v2 assert isinstance(v1, Vector) assert dot(v1, A.x) == x assert dot(v1, A.y) == y assert dot(v1, A.z) == z assert isinstance(v2, Vector) assert dot(v2, A.x) == x**2 assert dot(v2, A.y) == y**2 assert dot(v2, A.z) == z**2 assert isinstance(v3, Vector) # We probably shouldn't be using simplify in dot... assert dot(v3, A.x) == x**2 + x assert dot(v3, A.y) == y**2 + y assert dot(v3, A.z) == z**2 + z assert isinstance(v4, Vector) # We probably shouldn't be using simplify in dot... assert dot(v4, A.x) == x - x**2 assert dot(v4, A.y) == y - y**2 assert dot(v4, A.z) == z - z**2 assert v1.to_matrix(A) == Matrix([[x], [y], [z]]) q = symbols('q') B = A.orientnew('B', 'Axis', (q, A.x)) assert v1.to_matrix(B) == Matrix([[x], [ y * cos(q) + z * sin(q)], [-y * sin(q) + z * cos(q)]]) #Test the separate method B = ReferenceFrame('B') v5 = x*A.x + y*A.y + z*B.z assert Vector(0).separate() == {} assert v1.separate() == {A: v1} assert v5.separate() == {A: x*A.x + y*A.y, B: z*B.z} #Test the free_symbols property v6 = x*A.x + y*A.y + z*A.z assert v6.free_symbols(A) == {x,y,z} raises(TypeError, lambda: v3.applyfunc(v1)) def test_Vector_diffs(): q1, q2, q3, q4 = dynamicsymbols('q1 q2 q3 q4') q1d, q2d, q3d, q4d = dynamicsymbols('q1 q2 q3 q4', 1) q1dd, q2dd, q3dd, q4dd = dynamicsymbols('q1 q2 q3 q4', 2) N = ReferenceFrame('N') A = N.orientnew('A', 'Axis', [q3, N.z]) B = A.orientnew('B', 'Axis', [q2, A.x]) v1 = q2 * A.x + q3 * N.y v2 = q3 * B.x + v1 v3 = v1.dt(B) v4 = v2.dt(B) v5 = q1*A.x + q2*A.y + q3*A.z assert v1.dt(N) == q2d * A.x + q2 * q3d * A.y + q3d * N.y assert v1.dt(A) == q2d * A.x + q3 * q3d * N.x + q3d * N.y assert v1.dt(B) == (q2d * A.x + q3 * q3d * N.x + q3d *\ N.y - q3 * cos(q3) * q2d * N.z) assert v2.dt(N) == (q2d * A.x + (q2 + q3) * q3d * A.y + q3d * B.x + q3d * N.y) assert v2.dt(A) == q2d * A.x + q3d * B.x + q3 * q3d * N.x + q3d * N.y assert v2.dt(B) == (q2d * A.x + q3d * B.x + q3 * q3d * N.x + q3d * N.y - q3 * cos(q3) * q2d * N.z) assert v3.dt(N) == (q2dd * A.x + q2d * q3d * A.y + (q3d**2 + q3 * q3dd) * N.x + q3dd * N.y + (q3 * sin(q3) * q2d * q3d - cos(q3) * q2d * q3d - q3 * cos(q3) * q2dd) * N.z) assert v3.dt(A) == (q2dd * A.x + (2 * q3d**2 + q3 * q3dd) * N.x + (q3dd - q3 * q3d**2) * N.y + (q3 * sin(q3) * q2d * q3d - cos(q3) * q2d * q3d - q3 * cos(q3) * q2dd) * N.z) assert v3.dt(B) == (q2dd * A.x - q3 * cos(q3) * q2d**2 * A.y + (2 * q3d**2 + q3 * q3dd) * N.x + (q3dd - q3 * q3d**2) * N.y + (2 * q3 * sin(q3) * q2d * q3d - 2 * cos(q3) * q2d * q3d - q3 * cos(q3) * q2dd) * N.z) assert v4.dt(N) == (q2dd * A.x + q3d * (q2d + q3d) * A.y + q3dd * B.x + (q3d**2 + q3 * q3dd) * N.x + q3dd * N.y + (q3 * sin(q3) * q2d * q3d - cos(q3) * q2d * q3d - q3 * cos(q3) * q2dd) * N.z) assert v4.dt(A) == (q2dd * A.x + q3dd * B.x + (2 * q3d**2 + q3 * q3dd) * N.x + (q3dd - q3 * q3d**2) * N.y + (q3 * sin(q3) * q2d * q3d - cos(q3) * q2d * q3d - q3 * cos(q3) * q2dd) * N.z) assert v4.dt(B) == (q2dd * A.x - q3 * cos(q3) * q2d**2 * A.y + q3dd * B.x + (2 * q3d**2 + q3 * q3dd) * N.x + (q3dd - q3 * q3d**2) * N.y + (2 * q3 * sin(q3) * q2d * q3d - 2 * cos(q3) * q2d * q3d - q3 * cos(q3) * q2dd) * N.z) assert v5.dt(B) == q1d*A.x + (q3*q2d + q2d)*A.y + (-q2*q2d + q3d)*A.z assert v5.dt(A) == q1d*A.x + q2d*A.y + q3d*A.z assert v5.dt(N) == (-q2*q3d + q1d)*A.x + (q1*q3d + q2d)*A.y + q3d*A.z assert v3.diff(q1d, N) == 0 assert v3.diff(q2d, N) == A.x - q3 * cos(q3) * N.z assert v3.diff(q3d, N) == q3 * N.x + N.y assert v3.diff(q1d, A) == 0 assert v3.diff(q2d, A) == A.x - q3 * cos(q3) * N.z assert v3.diff(q3d, A) == q3 * N.x + N.y assert v3.diff(q1d, B) == 0 assert v3.diff(q2d, B) == A.x - q3 * cos(q3) * N.z assert v3.diff(q3d, B) == q3 * N.x + N.y assert v4.diff(q1d, N) == 0 assert v4.diff(q2d, N) == A.x - q3 * cos(q3) * N.z assert v4.diff(q3d, N) == B.x + q3 * N.x + N.y assert v4.diff(q1d, A) == 0 assert v4.diff(q2d, A) == A.x - q3 * cos(q3) * N.z assert v4.diff(q3d, A) == B.x + q3 * N.x + N.y assert v4.diff(q1d, B) == 0 assert v4.diff(q2d, B) == A.x - q3 * cos(q3) * N.z assert v4.diff(q3d, B) == B.x + q3 * N.x + N.y def test_vector_var_in_dcm(): N = ReferenceFrame('N') A = ReferenceFrame('A') B = ReferenceFrame('B') u1, u2, u3, u4 = dynamicsymbols('u1 u2 u3 u4') v = u1 * u2 * A.x + u3 * N.y + u4**2 * N.z assert v.diff(u1, N, var_in_dcm=False) == u2 * A.x assert v.diff(u1, A, var_in_dcm=False) == u2 * A.x assert v.diff(u3, N, var_in_dcm=False) == N.y assert v.diff(u3, A, var_in_dcm=False) == N.y assert v.diff(u3, B, var_in_dcm=False) == N.y assert v.diff(u4, N, var_in_dcm=False) == 2 * u4 * N.z raises(ValueError, lambda: v.diff(u1, N)) def test_vector_simplify(): x, y, z, k, n, m, w, f, s, A = symbols('x, y, z, k, n, m, w, f, s, A') N = ReferenceFrame('N') test1 = (1 / x + 1 / y) * N.x assert (test1 & N.x) != (x + y) / (x * y) test1 = test1.simplify() assert (test1 & N.x) == (x + y) / (x * y) test2 = (A**2 * s**4 / (4 * pi * k * m**3)) * N.x test2 = test2.simplify() assert (test2 & N.x) == (A**2 * s**4 / (4 * pi * k * m**3)) test3 = ((4 + 4 * x - 2 * (2 + 2 * x)) / (2 + 2 * x)) * N.x test3 = test3.simplify() assert (test3 & N.x) == 0 test4 = ((-4 * x * y**2 - 2 * y**3 - 2 * x**2 * y) / (x + y)**2) * N.x test4 = test4.simplify() assert (test4 & N.x) == -2 * y def test_vector_evalf(): a, b = symbols('a b') v = pi * A.x assert v.evalf(2) == Float('3.1416', 2) * A.x v = pi * A.x + 5 * a * A.y - b * A.z assert v.evalf(3) == Float('3.1416', 3) * A.x + Float('5', 3) * a * A.y - b * A.z assert v.evalf(5, subs={a: 1.234, b:5.8973}) == Float('3.1415926536', 5) * A.x + Float('6.17', 5) * A.y - Float('5.8973', 5) * A.z def test_vector_angle(): A = ReferenceFrame('A') v1 = A.x + A.y v2 = A.z assert v1.angle_between(v2) == pi/2 B = ReferenceFrame('B') B.orient_axis(A, A.x, pi) v3 = A.x v4 = B.x assert v3.angle_between(v4) == 0 def test_vector_xreplace(): x, y, z = symbols('x y z') v = x**2 * A.x + x*y * A.y + x*y*z * A.z assert v.xreplace({x : cos(x)}) == cos(x)**2 * A.x + y*cos(x) * A.y + y*z*cos(x) * A.z assert v.xreplace({x*y : pi}) == x**2 * A.x + pi * A.y + x*y*z * A.z assert v.xreplace({x*y*z : 1}) == x**2*A.x + x*y*A.y + A.z assert v.xreplace({x:1, z:0}) == A.x + y * A.y raises(TypeError, lambda: v.xreplace()) raises(TypeError, lambda: v.xreplace([x, y]))