Orienter classes (docstrings)

Orienter

class sympy.vector.orienters.Orienter(*args)

Super-class for all orienter classes.

rotation_matrix()

The rotation matrix corresponding to this orienter instance.

AxisOrienter

class sympy.vector.orienters.AxisOrienter(angle, axis)

Class to denote an axis orienter.

__init__(angle, axis)

Axis rotation is a rotation about an arbitrary axis by some angle. The angle is supplied as a SymPy expr scalar, and the axis is supplied as a Vector.

Parameters

angle : Expr

The angle by which the new system is to be rotated

axis : Vector

The axis around which the rotation has to be performed

Examples

>>> from sympy.vector import CoordSys3D
>>> from sympy import symbols
>>> q1 = symbols('q1')
>>> N = CoordSys3D('N')
>>> from sympy.vector import AxisOrienter
>>> orienter = AxisOrienter(q1, N.i + 2 * N.j)
>>> B = N.orient_new('B', (orienter, ))

rotation_matrix(system)

The rotation matrix corresponding to this orienter instance.

Parameters

system : CoordSys3D

The coordinate system wrt which the rotation matrix is to be computed

BodyOrienter

class sympy.vector.orienters.BodyOrienter(angle1, angle2, angle3, rot_order)

Class to denote a body-orienter.

__init__(angle1, angle2, angle3, rot_order)

Body orientation takes this coordinate system through three successive simple rotations.

Body fixed rotations include both Euler Angles and Tait-Bryan Angles, see https://en.wikipedia.org/wiki/Euler_angles.

Parameters

angle1, angle2, angle3 : Expr

Three successive angles to rotate the coordinate system by

rotation_order : string

String defining the order of axes for rotation

Examples

>>> from sympy.vector import CoordSys3D, BodyOrienter
>>> from sympy import symbols
>>> q1, q2, q3 = symbols('q1 q2 q3')
>>> N = CoordSys3D('N')

A ‘Body’ fixed rotation is described by three angles and three body-fixed rotation axes. To orient a coordinate system D with respect to N, each sequential rotation is always about the orthogonal unit vectors fixed to D. For example, a ‘123’ rotation will specify rotations about N.i, then D.j, then D.k. (Initially, D.i is same as N.i) Therefore,

>>> body_orienter = BodyOrienter(q1, q2, q3, '123')
>>> D = N.orient_new('D', (body_orienter, ))

is same as

>>> from sympy.vector import AxisOrienter
>>> axis_orienter1 = AxisOrienter(q1, N.i)
>>> D = N.orient_new('D', (axis_orienter1, ))
>>> axis_orienter2 = AxisOrienter(q2, D.j)
>>> D = D.orient_new('D', (axis_orienter2, ))
>>> axis_orienter3 = AxisOrienter(q3, D.k)
>>> D = D.orient_new('D', (axis_orienter3, ))

Acceptable rotation orders are of length 3, expressed in XYZ or 123, and cannot have a rotation about about an axis twice in a row.

>>> body_orienter1 = BodyOrienter(q1, q2, q3, '123')
>>> body_orienter2 = BodyOrienter(q1, q2, 0, 'ZXZ')
>>> body_orienter3 = BodyOrienter(0, 0, 0, 'XYX')

SpaceOrienter

class sympy.vector.orienters.SpaceOrienter(angle1, angle2, angle3, rot_order)

Class to denote a space-orienter.

__init__(angle1, angle2, angle3, rot_order)

Space rotation is similar to Body rotation, but the rotations are applied in the opposite order.

Parameters

angle1, angle2, angle3 : Expr

Three successive angles to rotate the coordinate system by

rotation_order : string

String defining the order of axes for rotation

Examples

>>> from sympy.vector import CoordSys3D, SpaceOrienter
>>> from sympy import symbols
>>> q1, q2, q3 = symbols('q1 q2 q3')
>>> N = CoordSys3D('N')

To orient a coordinate system D with respect to N, each sequential rotation is always about N’s orthogonal unit vectors. For example, a ‘123’ rotation will specify rotations about N.i, then N.j, then N.k. Therefore,

>>> space_orienter = SpaceOrienter(q1, q2, q3, '312')
>>> D = N.orient_new('D', (space_orienter, ))

is same as

>>> from sympy.vector import AxisOrienter
>>> axis_orienter1 = AxisOrienter(q1, N.i)
>>> B = N.orient_new('B', (axis_orienter1, ))
>>> axis_orienter2 = AxisOrienter(q2, N.j)
>>> C = B.orient_new('C', (axis_orienter2, ))
>>> axis_orienter3 = AxisOrienter(q3, N.k)
>>> D = C.orient_new('C', (axis_orienter3, ))

See also

BodyOrienter

Orienter to orient systems wrt Euler angles.

QuaternionOrienter

class sympy.vector.orienters.QuaternionOrienter(q0, q1, q2, q3)

Class to denote a quaternion-orienter.

__init__(angle1, angle2, angle3, rot_order)

Quaternion orientation orients the new CoordSys3D with Quaternions, defined as a finite rotation about lambda, a unit vector, by some amount theta.

This orientation is described by four parameters:

q0 = cos(theta/2)

q1 = lambda_x sin(theta/2)

q2 = lambda_y sin(theta/2)

q3 = lambda_z sin(theta/2)

Quaternion does not take in a rotation order.

Parameters

q0, q1, q2, q3 : Expr

The quaternions to rotate the coordinate system by

Examples

>>> from sympy.vector import CoordSys3D
>>> from sympy import symbols
>>> q0, q1, q2, q3 = symbols('q0 q1 q2 q3')
>>> N = CoordSys3D('N')
>>> from sympy.vector import QuaternionOrienter
>>> q_orienter = QuaternionOrienter(q0, q1, q2, q3)
>>> B = N.orient_new('B', (q_orienter, ))