from sympy import S, Integral, sin, cos, pi, sqrt, symbols from sympy.physics.vector import Dyadic, Point, ReferenceFrame, Vector from sympy.physics.vector.functions import (cross, dot, express, time_derivative, kinematic_equations, outer, partial_velocity, get_motion_params, dynamicsymbols) from sympy.testing.pytest import raises Vector.simp = True q1, q2, q3, q4, q5 = symbols('q1 q2 q3 q4 q5') N = ReferenceFrame('N') A = N.orientnew('A', 'Axis', [q1, N.z]) B = A.orientnew('B', 'Axis', [q2, A.x]) C = B.orientnew('C', 'Axis', [q3, B.y]) def test_dot(): assert dot(A.x, A.x) == 1 assert dot(A.x, A.y) == 0 assert dot(A.x, A.z) == 0 assert dot(A.y, A.x) == 0 assert dot(A.y, A.y) == 1 assert dot(A.y, A.z) == 0 assert dot(A.z, A.x) == 0 assert dot(A.z, A.y) == 0 assert dot(A.z, A.z) == 1 def test_dot_different_frames(): assert dot(N.x, A.x) == cos(q1) assert dot(N.x, A.y) == -sin(q1) assert dot(N.x, A.z) == 0 assert dot(N.y, A.x) == sin(q1) assert dot(N.y, A.y) == cos(q1) assert dot(N.y, A.z) == 0 assert dot(N.z, A.x) == 0 assert dot(N.z, A.y) == 0 assert dot(N.z, A.z) == 1 assert dot(N.x, A.x + A.y) == sqrt(2)*cos(q1 + pi/4) == dot(A.x + A.y, N.x) assert dot(A.x, C.x) == cos(q3) assert dot(A.x, C.y) == 0 assert dot(A.x, C.z) == sin(q3) assert dot(A.y, C.x) == sin(q2)*sin(q3) assert dot(A.y, C.y) == cos(q2) assert dot(A.y, C.z) == -sin(q2)*cos(q3) assert dot(A.z, C.x) == -cos(q2)*sin(q3) assert dot(A.z, C.y) == sin(q2) assert dot(A.z, C.z) == cos(q2)*cos(q3) def test_cross(): assert cross(A.x, A.x) == 0 assert cross(A.x, A.y) == A.z assert cross(A.x, A.z) == -A.y assert cross(A.y, A.x) == -A.z assert cross(A.y, A.y) == 0 assert cross(A.y, A.z) == A.x assert cross(A.z, A.x) == A.y assert cross(A.z, A.y) == -A.x assert cross(A.z, A.z) == 0 def test_cross_different_frames(): assert cross(N.x, A.x) == sin(q1)*A.z assert cross(N.x, A.y) == cos(q1)*A.z assert cross(N.x, A.z) == -sin(q1)*A.x - cos(q1)*A.y assert cross(N.y, A.x) == -cos(q1)*A.z assert cross(N.y, A.y) == sin(q1)*A.z assert cross(N.y, A.z) == cos(q1)*A.x - sin(q1)*A.y assert cross(N.z, A.x) == A.y assert cross(N.z, A.y) == -A.x assert cross(N.z, A.z) == 0 assert cross(N.x, A.x) == sin(q1)*A.z assert cross(N.x, A.y) == cos(q1)*A.z assert cross(N.x, A.x + A.y) == sin(q1)*A.z + cos(q1)*A.z assert cross(A.x + A.y, N.x) == -sin(q1)*A.z - cos(q1)*A.z assert cross(A.x, C.x) == sin(q3)*C.y assert cross(A.x, C.y) == -sin(q3)*C.x + cos(q3)*C.z assert cross(A.x, C.z) == -cos(q3)*C.y assert cross(C.x, A.x) == -sin(q3)*C.y assert cross(C.y, A.x) == sin(q3)*C.x - cos(q3)*C.z assert cross(C.z, A.x) == cos(q3)*C.y def test_operator_match(): """Test that the output of dot, cross, outer functions match operator behavior. """ A = ReferenceFrame('A') v = A.x + A.y d = v | v zerov = Vector(0) zerod = Dyadic(0) # dot products assert d & d == dot(d, d) assert d & zerod == dot(d, zerod) assert zerod & d == dot(zerod, d) assert d & v == dot(d, v) assert v & d == dot(v, d) assert d & zerov == dot(d, zerov) assert zerov & d == dot(zerov, d) raises(TypeError, lambda: dot(d, S.Zero)) raises(TypeError, lambda: dot(S.Zero, d)) raises(TypeError, lambda: dot(d, 0)) raises(TypeError, lambda: dot(0, d)) assert v & v == dot(v, v) assert v & zerov == dot(v, zerov) assert zerov & v == dot(zerov, v) raises(TypeError, lambda: dot(v, S.Zero)) raises(TypeError, lambda: dot(S.Zero, v)) raises(TypeError, lambda: dot(v, 0)) raises(TypeError, lambda: dot(0, v)) # cross products raises(TypeError, lambda: cross(d, d)) raises(TypeError, lambda: cross(d, zerod)) raises(TypeError, lambda: cross(zerod, d)) assert d ^ v == cross(d, v) assert v ^ d == cross(v, d) assert d ^ zerov == cross(d, zerov) assert zerov ^ d == cross(zerov, d) assert zerov ^ d == cross(zerov, d) raises(TypeError, lambda: cross(d, S.Zero)) raises(TypeError, lambda: cross(S.Zero, d)) raises(TypeError, lambda: cross(d, 0)) raises(TypeError, lambda: cross(0, d)) assert v ^ v == cross(v, v) assert v ^ zerov == cross(v, zerov) assert zerov ^ v == cross(zerov, v) raises(TypeError, lambda: cross(v, S.Zero)) raises(TypeError, lambda: cross(S.Zero, v)) raises(TypeError, lambda: cross(v, 0)) raises(TypeError, lambda: cross(0, v)) # outer products raises(TypeError, lambda: outer(d, d)) raises(TypeError, lambda: outer(d, zerod)) raises(TypeError, lambda: outer(zerod, d)) raises(TypeError, lambda: outer(d, v)) raises(TypeError, lambda: outer(v, d)) raises(TypeError, lambda: outer(d, zerov)) raises(TypeError, lambda: outer(zerov, d)) raises(TypeError, lambda: outer(zerov, d)) raises(TypeError, lambda: outer(d, S.Zero)) raises(TypeError, lambda: outer(S.Zero, d)) raises(TypeError, lambda: outer(d, 0)) raises(TypeError, lambda: outer(0, d)) assert v | v == outer(v, v) assert v | zerov == outer(v, zerov) assert zerov | v == outer(zerov, v) raises(TypeError, lambda: outer(v, S.Zero)) raises(TypeError, lambda: outer(S.Zero, v)) raises(TypeError, lambda: outer(v, 0)) raises(TypeError, lambda: outer(0, v)) def test_express(): assert express(Vector(0), N) == Vector(0) assert express(S.Zero, N) is S.Zero assert express(A.x, C) == cos(q3)*C.x + sin(q3)*C.z assert express(A.y, C) == sin(q2)*sin(q3)*C.x + cos(q2)*C.y - \ sin(q2)*cos(q3)*C.z assert express(A.z, C) == -sin(q3)*cos(q2)*C.x + sin(q2)*C.y + \ cos(q2)*cos(q3)*C.z assert express(A.x, N) == cos(q1)*N.x + sin(q1)*N.y assert express(A.y, N) == -sin(q1)*N.x + cos(q1)*N.y assert express(A.z, N) == N.z assert express(A.x, A) == A.x assert express(A.y, A) == A.y assert express(A.z, A) == A.z assert express(A.x, B) == B.x assert express(A.y, B) == cos(q2)*B.y - sin(q2)*B.z assert express(A.z, B) == sin(q2)*B.y + cos(q2)*B.z assert express(A.x, C) == cos(q3)*C.x + sin(q3)*C.z assert express(A.y, C) == sin(q2)*sin(q3)*C.x + cos(q2)*C.y - \ sin(q2)*cos(q3)*C.z assert express(A.z, C) == -sin(q3)*cos(q2)*C.x + sin(q2)*C.y + \ cos(q2)*cos(q3)*C.z # Check to make sure UnitVectors get converted properly assert express(N.x, N) == N.x assert express(N.y, N) == N.y assert express(N.z, N) == N.z assert express(N.x, A) == (cos(q1)*A.x - sin(q1)*A.y) assert express(N.y, A) == (sin(q1)*A.x + cos(q1)*A.y) assert express(N.z, A) == A.z assert express(N.x, B) == (cos(q1)*B.x - sin(q1)*cos(q2)*B.y + sin(q1)*sin(q2)*B.z) assert express(N.y, B) == (sin(q1)*B.x + cos(q1)*cos(q2)*B.y - sin(q2)*cos(q1)*B.z) assert express(N.z, B) == (sin(q2)*B.y + cos(q2)*B.z) assert express(N.x, C) == ( (cos(q1)*cos(q3) - sin(q1)*sin(q2)*sin(q3))*C.x - sin(q1)*cos(q2)*C.y + (sin(q3)*cos(q1) + sin(q1)*sin(q2)*cos(q3))*C.z) assert express(N.y, C) == ( (sin(q1)*cos(q3) + sin(q2)*sin(q3)*cos(q1))*C.x + cos(q1)*cos(q2)*C.y + (sin(q1)*sin(q3) - sin(q2)*cos(q1)*cos(q3))*C.z) assert express(N.z, C) == (-sin(q3)*cos(q2)*C.x + sin(q2)*C.y + cos(q2)*cos(q3)*C.z) assert express(A.x, N) == (cos(q1)*N.x + sin(q1)*N.y) assert express(A.y, N) == (-sin(q1)*N.x + cos(q1)*N.y) assert express(A.z, N) == N.z assert express(A.x, A) == A.x assert express(A.y, A) == A.y assert express(A.z, A) == A.z assert express(A.x, B) == B.x assert express(A.y, B) == (cos(q2)*B.y - sin(q2)*B.z) assert express(A.z, B) == (sin(q2)*B.y + cos(q2)*B.z) assert express(A.x, C) == (cos(q3)*C.x + sin(q3)*C.z) assert express(A.y, C) == (sin(q2)*sin(q3)*C.x + cos(q2)*C.y - sin(q2)*cos(q3)*C.z) assert express(A.z, C) == (-sin(q3)*cos(q2)*C.x + sin(q2)*C.y + cos(q2)*cos(q3)*C.z) assert express(B.x, N) == (cos(q1)*N.x + sin(q1)*N.y) assert express(B.y, N) == (-sin(q1)*cos(q2)*N.x + cos(q1)*cos(q2)*N.y + sin(q2)*N.z) assert express(B.z, N) == (sin(q1)*sin(q2)*N.x - sin(q2)*cos(q1)*N.y + cos(q2)*N.z) assert express(B.x, A) == A.x assert express(B.y, A) == (cos(q2)*A.y + sin(q2)*A.z) assert express(B.z, A) == (-sin(q2)*A.y + cos(q2)*A.z) assert express(B.x, B) == B.x assert express(B.y, B) == B.y assert express(B.z, B) == B.z assert express(B.x, C) == (cos(q3)*C.x + sin(q3)*C.z) assert express(B.y, C) == C.y assert express(B.z, C) == (-sin(q3)*C.x + cos(q3)*C.z) assert express(C.x, N) == ( (cos(q1)*cos(q3) - sin(q1)*sin(q2)*sin(q3))*N.x + (sin(q1)*cos(q3) + sin(q2)*sin(q3)*cos(q1))*N.y - sin(q3)*cos(q2)*N.z) assert express(C.y, N) == ( -sin(q1)*cos(q2)*N.x + cos(q1)*cos(q2)*N.y + sin(q2)*N.z) assert express(C.z, N) == ( (sin(q3)*cos(q1) + sin(q1)*sin(q2)*cos(q3))*N.x + (sin(q1)*sin(q3) - sin(q2)*cos(q1)*cos(q3))*N.y + cos(q2)*cos(q3)*N.z) assert express(C.x, A) == (cos(q3)*A.x + sin(q2)*sin(q3)*A.y - sin(q3)*cos(q2)*A.z) assert express(C.y, A) == (cos(q2)*A.y + sin(q2)*A.z) assert express(C.z, A) == (sin(q3)*A.x - sin(q2)*cos(q3)*A.y + cos(q2)*cos(q3)*A.z) assert express(C.x, B) == (cos(q3)*B.x - sin(q3)*B.z) assert express(C.y, B) == B.y assert express(C.z, B) == (sin(q3)*B.x + cos(q3)*B.z) assert express(C.x, C) == C.x assert express(C.y, C) == C.y assert express(C.z, C) == C.z == (C.z) # Check to make sure Vectors get converted back to UnitVectors assert N.x == express((cos(q1)*A.x - sin(q1)*A.y), N) assert N.y == express((sin(q1)*A.x + cos(q1)*A.y), N) assert N.x == express((cos(q1)*B.x - sin(q1)*cos(q2)*B.y + sin(q1)*sin(q2)*B.z), N) assert N.y == express((sin(q1)*B.x + cos(q1)*cos(q2)*B.y - sin(q2)*cos(q1)*B.z), N) assert N.z == express((sin(q2)*B.y + cos(q2)*B.z), N) """ These don't really test our code, they instead test the auto simplification (or lack thereof) of SymPy. assert N.x == express(( (cos(q1)*cos(q3)-sin(q1)*sin(q2)*sin(q3))*C.x - sin(q1)*cos(q2)*C.y + (sin(q3)*cos(q1)+sin(q1)*sin(q2)*cos(q3))*C.z), N) assert N.y == express(( (sin(q1)*cos(q3) + sin(q2)*sin(q3)*cos(q1))*C.x + cos(q1)*cos(q2)*C.y + (sin(q1)*sin(q3) - sin(q2)*cos(q1)*cos(q3))*C.z), N) assert N.z == express((-sin(q3)*cos(q2)*C.x + sin(q2)*C.y + cos(q2)*cos(q3)*C.z), N) """ assert A.x == express((cos(q1)*N.x + sin(q1)*N.y), A) assert A.y == express((-sin(q1)*N.x + cos(q1)*N.y), A) assert A.y == express((cos(q2)*B.y - sin(q2)*B.z), A) assert A.z == express((sin(q2)*B.y + cos(q2)*B.z), A) assert A.x == express((cos(q3)*C.x + sin(q3)*C.z), A) # Tripsimp messes up here too. #print express((sin(q2)*sin(q3)*C.x + cos(q2)*C.y - # sin(q2)*cos(q3)*C.z), A) assert A.y == express((sin(q2)*sin(q3)*C.x + cos(q2)*C.y - sin(q2)*cos(q3)*C.z), A) assert A.z == express((-sin(q3)*cos(q2)*C.x + sin(q2)*C.y + cos(q2)*cos(q3)*C.z), A) assert B.x == express((cos(q1)*N.x + sin(q1)*N.y), B) assert B.y == express((-sin(q1)*cos(q2)*N.x + cos(q1)*cos(q2)*N.y + sin(q2)*N.z), B) assert B.z == express((sin(q1)*sin(q2)*N.x - sin(q2)*cos(q1)*N.y + cos(q2)*N.z), B) assert B.y == express((cos(q2)*A.y + sin(q2)*A.z), B) assert B.z == express((-sin(q2)*A.y + cos(q2)*A.z), B) assert B.x == express((cos(q3)*C.x + sin(q3)*C.z), B) assert B.z == express((-sin(q3)*C.x + cos(q3)*C.z), B) """ assert C.x == express(( (cos(q1)*cos(q3)-sin(q1)*sin(q2)*sin(q3))*N.x + (sin(q1)*cos(q3)+sin(q2)*sin(q3)*cos(q1))*N.y - sin(q3)*cos(q2)*N.z), C) assert C.y == express(( -sin(q1)*cos(q2)*N.x + cos(q1)*cos(q2)*N.y + sin(q2)*N.z), C) assert C.z == express(( (sin(q3)*cos(q1)+sin(q1)*sin(q2)*cos(q3))*N.x + (sin(q1)*sin(q3)-sin(q2)*cos(q1)*cos(q3))*N.y + cos(q2)*cos(q3)*N.z), C) """ assert C.x == express((cos(q3)*A.x + sin(q2)*sin(q3)*A.y - sin(q3)*cos(q2)*A.z), C) assert C.y == express((cos(q2)*A.y + sin(q2)*A.z), C) assert C.z == express((sin(q3)*A.x - sin(q2)*cos(q3)*A.y + cos(q2)*cos(q3)*A.z), C) assert C.x == express((cos(q3)*B.x - sin(q3)*B.z), C) assert C.z == express((sin(q3)*B.x + cos(q3)*B.z), C) def test_time_derivative(): #The use of time_derivative for calculations pertaining to scalar #fields has been tested in test_coordinate_vars in test_essential.py A = ReferenceFrame('A') q = dynamicsymbols('q') qd = dynamicsymbols('q', 1) B = A.orientnew('B', 'Axis', [q, A.z]) d = A.x | A.x assert time_derivative(d, B) == (-qd) * (A.y | A.x) + \ (-qd) * (A.x | A.y) d1 = A.x | B.y assert time_derivative(d1, A) == - qd*(A.x|B.x) assert time_derivative(d1, B) == - qd*(A.y|B.y) d2 = A.x | B.x assert time_derivative(d2, A) == qd*(A.x|B.y) assert time_derivative(d2, B) == - qd*(A.y|B.x) d3 = A.x | B.z assert time_derivative(d3, A) == 0 assert time_derivative(d3, B) == - qd*(A.y|B.z) 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) C = B.orientnew('C', 'Axis', [q4, B.x]) v1 = q1 * A.z v2 = q2*A.x + q3*B.y v3 = q1*A.x + q2*A.y + q3*A.z assert time_derivative(B.x, C) == 0 assert time_derivative(B.y, C) == - q4d*B.z assert time_derivative(B.z, C) == q4d*B.y assert time_derivative(v1, B) == q1d*A.z assert time_derivative(v1, C) == - q1*sin(q)*q4d*A.x + \ q1*cos(q)*q4d*A.y + q1d*A.z assert time_derivative(v2, A) == q2d*A.x - q3*qd*B.x + q3d*B.y assert time_derivative(v2, C) == q2d*A.x - q2*qd*A.y + \ q2*sin(q)*q4d*A.z + q3d*B.y - q3*q4d*B.z assert time_derivative(v3, B) == (q2*qd + q1d)*A.x + \ (-q1*qd + q2d)*A.y + q3d*A.z assert time_derivative(d, C) == - qd*(A.y|A.x) + \ sin(q)*q4d*(A.z|A.x) - qd*(A.x|A.y) + sin(q)*q4d*(A.x|A.z) raises(ValueError, lambda: time_derivative(B.x, C, order=0.5)) raises(ValueError, lambda: time_derivative(B.x, C, order=-1)) def test_get_motion_methods(): #Initialization t = dynamicsymbols._t s1, s2, s3 = symbols('s1 s2 s3') S1, S2, S3 = symbols('S1 S2 S3') S4, S5, S6 = symbols('S4 S5 S6') t1, t2 = symbols('t1 t2') a, b, c = dynamicsymbols('a b c') ad, bd, cd = dynamicsymbols('a b c', 1) a2d, b2d, c2d = dynamicsymbols('a b c', 2) v0 = S1*N.x + S2*N.y + S3*N.z v01 = S4*N.x + S5*N.y + S6*N.z v1 = s1*N.x + s2*N.y + s3*N.z v2 = a*N.x + b*N.y + c*N.z v2d = ad*N.x + bd*N.y + cd*N.z v2dd = a2d*N.x + b2d*N.y + c2d*N.z #Test position parameter assert get_motion_params(frame = N) == (0, 0, 0) assert get_motion_params(N, position=v1) == (0, 0, v1) assert get_motion_params(N, position=v2) == (v2dd, v2d, v2) #Test velocity parameter assert get_motion_params(N, velocity=v1) == (0, v1, v1 * t) assert get_motion_params(N, velocity=v1, position=v0, timevalue1=t1) == \ (0, v1, v0 + v1*(t - t1)) answer = get_motion_params(N, velocity=v1, position=v2, timevalue1=t1) answer_expected = (0, v1, v1*t - v1*t1 + v2.subs(t, t1)) assert answer == answer_expected answer = get_motion_params(N, velocity=v2, position=v0, timevalue1=t1) integral_vector = Integral(a, (t, t1, t))*N.x + Integral(b, (t, t1, t))*N.y \ + Integral(c, (t, t1, t))*N.z answer_expected = (v2d, v2, v0 + integral_vector) assert answer == answer_expected #Test acceleration parameter assert get_motion_params(N, acceleration=v1) == \ (v1, v1 * t, v1 * t**2/2) assert get_motion_params(N, acceleration=v1, velocity=v0, position=v2, timevalue1=t1, timevalue2=t2) == \ (v1, (v0 + v1*t - v1*t2), -v0*t1 + v1*t**2/2 + v1*t2*t1 - \ v1*t1**2/2 + t*(v0 - v1*t2) + \ v2.subs(t, t1)) assert get_motion_params(N, acceleration=v1, velocity=v0, position=v01, timevalue1=t1, timevalue2=t2) == \ (v1, v0 + v1*t - v1*t2, -v0*t1 + v01 + v1*t**2/2 + \ v1*t2*t1 - v1*t1**2/2 + \ t*(v0 - v1*t2)) answer = get_motion_params(N, acceleration=a*N.x, velocity=S1*N.x, position=S2*N.x, timevalue1=t1, timevalue2=t2) i1 = Integral(a, (t, t2, t)) answer_expected = (a*N.x, (S1 + i1)*N.x, \ (S2 + Integral(S1 + i1, (t, t1, t)))*N.x) assert answer == answer_expected def test_kin_eqs(): q0, q1, q2, q3 = dynamicsymbols('q0 q1 q2 q3') q0d, q1d, q2d, q3d = dynamicsymbols('q0 q1 q2 q3', 1) u1, u2, u3 = dynamicsymbols('u1 u2 u3') ke = kinematic_equations([u1,u2,u3], [q1,q2,q3], 'body', 313) assert ke == kinematic_equations([u1,u2,u3], [q1,q2,q3], 'body', '313') kds = kinematic_equations([u1, u2, u3], [q0, q1, q2, q3], 'quaternion') assert kds == [-0.5 * q0 * u1 - 0.5 * q2 * u3 + 0.5 * q3 * u2 + q1d, -0.5 * q0 * u2 + 0.5 * q1 * u3 - 0.5 * q3 * u1 + q2d, -0.5 * q0 * u3 - 0.5 * q1 * u2 + 0.5 * q2 * u1 + q3d, 0.5 * q1 * u1 + 0.5 * q2 * u2 + 0.5 * q3 * u3 + q0d] raises(ValueError, lambda: kinematic_equations([u1, u2, u3], [q0, q1, q2], 'quaternion')) raises(ValueError, lambda: kinematic_equations([u1, u2, u3], [q0, q1, q2, q3], 'quaternion', '123')) raises(ValueError, lambda: kinematic_equations([u1, u2, u3], [q0, q1, q2, q3], 'foo')) raises(TypeError, lambda: kinematic_equations(u1, [q0, q1, q2, q3], 'quaternion')) raises(TypeError, lambda: kinematic_equations([u1], [q0, q1, q2, q3], 'quaternion')) raises(TypeError, lambda: kinematic_equations([u1, u2, u3], q0, 'quaternion')) raises(ValueError, lambda: kinematic_equations([u1, u2, u3], [q0, q1, q2, q3], 'body')) raises(ValueError, lambda: kinematic_equations([u1, u2, u3], [q0, q1, q2, q3], 'space')) raises(ValueError, lambda: kinematic_equations([u1, u2, u3], [q0, q1, q2], 'body', '222')) assert kinematic_equations([0, 0, 0], [q0, q1, q2], 'space') == [S.Zero, S.Zero, S.Zero] def test_partial_velocity(): q1, q2, q3, u1, u2, u3 = dynamicsymbols('q1 q2 q3 u1 u2 u3') u4, u5 = dynamicsymbols('u4, u5') r = symbols('r') N = ReferenceFrame('N') Y = N.orientnew('Y', 'Axis', [q1, N.z]) L = Y.orientnew('L', 'Axis', [q2, Y.x]) R = L.orientnew('R', 'Axis', [q3, L.y]) R.set_ang_vel(N, u1 * L.x + u2 * L.y + u3 * L.z) C = Point('C') C.set_vel(N, u4 * L.x + u5 * (Y.z ^ L.x)) Dmc = C.locatenew('Dmc', r * L.z) Dmc.v2pt_theory(C, N, R) vel_list = [Dmc.vel(N), C.vel(N), R.ang_vel_in(N)] u_list = [u1, u2, u3, u4, u5] assert (partial_velocity(vel_list, u_list, N) == [[- r*L.y, r*L.x, 0, L.x, cos(q2)*L.y - sin(q2)*L.z], [0, 0, 0, L.x, cos(q2)*L.y - sin(q2)*L.z], [L.x, L.y, L.z, 0, 0]]) # Make sure that partial velocities can be computed regardless if the # orientation between frames is defined or not. A = ReferenceFrame('A') B = ReferenceFrame('B') v = u4 * A.x + u5 * B.y assert partial_velocity((v, ), (u4, u5), A) == [[A.x, B.y]] raises(TypeError, lambda: partial_velocity(Dmc.vel(N), u_list, N)) raises(TypeError, lambda: partial_velocity(vel_list, u1, N)) def test_dynamicsymbols(): #Tests to check the assumptions applied to dynamicsymbols f1 = dynamicsymbols('f1') f2 = dynamicsymbols('f2', real=True) f3 = dynamicsymbols('f3', positive=True) f4, f5 = dynamicsymbols('f4,f5', commutative=False) f6 = dynamicsymbols('f6', integer=True) assert f1.is_real is None assert f2.is_real assert f3.is_positive assert f4*f5 != f5*f4 assert f6.is_integer