Physlib

Physlib.Mathematics.SO3.Basic

22 declarations

definition

The special orthogonal group SO(3)SO(3)

#SO3

The set of 3×33 \times 3 real matrices AA such that detA=1\det A = 1 and AA=IAA^\top = I, where AA^\top denotes the transpose of AA and II is the 3×33 \times 3 identity matrix.

instance

The group structure on SO(3)SO(3) under matrix multiplication

#SO3Group

The set SO(3)SO(3), consisting of 3×33 \times 3 real matrices AA such that detA=1\det A = 1 and AA=IAA^\top = I (where II is the identity matrix and AA^\top is the transpose), forms a group. The group operation is defined by matrix multiplication, the identity element is the 3×33 \times 3 identity matrix II, and the inverse of a matrix ASO(3)A \in SO(3) is its transpose AA^\top.

definition

Notation for SO(3)SO(3)

#SO3_notation

The symbol SO(3)SO(3) is defined as a notation to represent the special orthogonal group in three dimensions, SO3SO_3.

instance

Topological space structure on SO(3)SO(3)

#instTopologicalSpaceSO3

The topological space structure on the special orthogonal group SO(3)SO(3) is defined as the subspace topology (or subtype topology) inherited from the space of 3×33 \times 3 real matrices R3×3\mathbb{R}^{3 \times 3}.

theorem

The group inverse in SO(3)SO(3) is the matrix inverse

#coe_inv

For any element AA in the special orthogonal group SO(3)SO(3), the 3×33 \times 3 real matrix representing the group inverse A1A^{-1} is equal to the matrix inverse of the 3×33 \times 3 real matrix representing AA.

definition

Group homomorphism SO(3)GL(3,R)SO(3) \to GL(3, \mathbb{R})

#toGL

This definition defines the natural group homomorphism from the special orthogonal group SO(3)SO(3) to the general linear group GL(3,R)GL(3, \mathbb{R}). It maps each 3×33 \times 3 real matrix AA in SO(3)SO(3) to itself, regarded as an invertible matrix in GL(3,R)GL(3, \mathbb{R}).

theorem

The inclusion SO(3)M3(R)SO(3) \to M_3(\mathbb{R}) equals the composition SO(3)GL(3,R)M3(R)SO(3) \to GL(3, \mathbb{R}) \to M_3(\mathbb{R})

#subtype_val_eq_toGL

The inclusion map that views an element of the special orthogonal group SO(3)SO(3) as a 3×33 \times 3 real matrix in M3(R)M_3(\mathbb{R}) is equal to the composition of the natural group homomorphism SO(3)GL(3,R)SO(3) \to GL(3, \mathbb{R}) and the inclusion map from the general linear group GL(3,R)GL(3, \mathbb{R}) to M3(R)M_3(\mathbb{R}).

theorem

The inclusion SO(3)GL(3,R)SO(3) \to GL(3, \mathbb{R}) is injective

#toGL_injective

The group homomorphism ι:SO(3)GL(3,R)\iota: SO(3) \to GL(3, \mathbb{R}) that maps each matrix AA in the special orthogonal group SO(3)SO(3) to itself as an element of the general linear group GL(3,R)GL(3, \mathbb{R}) is injective. Here, SO(3)SO(3) is the group of 3×33 \times 3 real matrices AA such that detA=1\det A = 1 and AA=IAA^\top = I.

definition

Group homomorphism SO(3)M3(R)×M3(R)opSO(3) \to M_3(\mathbb{R}) \times M_3(\mathbb{R})^{op} mapping A(A,A)A \mapsto (A, A^\top)

#toProd

The group homomorphism toProd\text{toProd} maps an element AA of the special orthogonal group SO(3)SO(3) to the pair (A,A)(A, A^\top) in the product of the monoid of 3×33 \times 3 real matrices M3(R)M_3(\mathbb{R}) and its opposite monoid M3(R)opM_3(\mathbb{R})^{op}. Here, SO(3)SO(3) consists of 3×33 \times 3 real matrices AA satisfying AA=IAA^\top = I and detA=1\det A = 1, and AA^\top denotes the transpose (which is the inverse A1A^{-1} for elements of SO(3)SO(3)).

theorem

toProd(A)=(A,A)\text{toProd}(A) = (A, A^\top) for ASO(3)A \in SO(3)

#toProd_eq_transpose

For any element AA in the special orthogonal group SO(3)SO(3), the group homomorphism toProd\text{toProd} maps AA to the pair (A,A)(A, A^\top), where AA is the underlying 3×33 \times 3 real matrix and AA^\top denotes its transpose.

theorem

The map A(A,A)A \mapsto (A, A^\top) on SO(3)SO(3) is injective

#toProd_injective

The map toProd:SO(3)M3(R)×M3(R)op\text{toProd} : SO(3) \to M_3(\mathbb{R}) \times M_3(\mathbb{R})^{op}, which sends an element AA of the special orthogonal group SO(3)SO(3) to the pair (A,A)(A, A^\top), is injective. Here, SO(3)SO(3) is the group of 3×33 \times 3 real matrices with detA=1\det A = 1 and AA=IAA^\top = I, and AA^\top denotes the transpose of AA.

theorem

The map A(A,A)A \mapsto (A, A^\top) on SO(3)SO(3) is continuous

#toProd_continuous

The group homomorphism toProd:SO(3)M3(R)×M3(R)op\text{toProd} : SO(3) \to M_3(\mathbb{R}) \times M_3(\mathbb{R})^{op}, which maps an element AA of the special orthogonal group SO(3)SO(3) to the pair (A,A)(A, A^\top), is continuous. Here, SO(3)SO(3) is equipped with the subspace topology inherited from the space of 3×33 \times 3 real matrices M3(R)M_3(\mathbb{R}).

theorem

The map A(A,A)A \mapsto (A, A^\top) on SO(3)SO(3) is a topological embedding

#toProd_embedding

The map toProd:SO(3)M3(R)×M3(R)op\text{toProd}: SO(3) \to M_3(\mathbb{R}) \times M_3(\mathbb{R})^{op}, which maps an element AA of the special orthogonal group SO(3)SO(3) to the pair (A,A)(A, A^\top), is a topological embedding. Here, SO(3)SO(3) is the group of 3×33 \times 3 real matrices AA such that detA=1\det A = 1 and AA=IAA^\top = I, and M3(R)opM_3(\mathbb{R})^{op} denotes the opposite monoid of 3×33 \times 3 real matrices.

theorem

The inclusion of SO(3)SO(3) into GL(3,R)GL(3, \mathbb{R}) is a topological embedding

#toGL_embedding

The natural map ι:SO(3)GL(3,R)\iota: SO(3) \to GL(3, \mathbb{R}) that sends each matrix AA in the special orthogonal group to itself in the general linear group is a topological embedding. Here, SO(3)SO(3) is the group of 3×33 \times 3 real matrices AA satisfying detA=1\det A = 1 and AA=IAA^\top = I (where II is the identity matrix and AA^\top is the transpose), and GL(3,R)GL(3, \mathbb{R}) is the group of invertible 3×33 \times 3 real matrices.

instance

SO(3)SO(3) is a Topological Group

#instIsTopologicalGroup

The special orthogonal group SO(3)SO(3), consisting of 3×33 \times 3 real matrices AA such that detA=1\det A = 1 and AA=IAA^\top = I (where II is the identity matrix and AA^\top is the transpose), is a topological group. This means that, when SO(3)SO(3) is equipped with the subspace topology inherited from the space of real 3×33 \times 3 matrices R3×3\mathbb{R}^{3 \times 3}, the group multiplication (A,B)AB(A, B) \mapsto AB and the inversion operation AA1=AA \mapsto A^{-1} = A^\top are continuous functions.

theorem

det(AI)=0\det(A - I) = 0 for ASO(3)A \in SO(3)

#det_minus_id

For any matrix AA in the special orthogonal group SO(3)SO(3), the determinant of the matrix AIA - I is equal to zero, where II denotes the 3×33 \times 3 identity matrix.

theorem

det(IA)=0\det(I - A) = 0 for ASO(3)A \in SO(3)

#det_id_minus

For any matrix AA in the special orthogonal group SO(3)SO(3), the determinant of the matrix IAI - A is equal to zero, where II denotes the 3×33 \times 3 identity matrix.

theorem

1spectrum(A)1 \in \text{spectrum}(A) for ASO(3)A \in SO(3)

#one_in_spectrum

For every matrix AA in the special orthogonal group SO(3)SO(3), the real number 11 is in the spectrum of AA. Here, SO(3)SO(3) is the group of 3×33 \times 3 real matrices AA such that detA=1\det A = 1 and AA=IAA^\top = I.

definition

Linear endomorphism associated with ASO(3)A \in \text{SO}(3)

#toEnd

Given an element AA of the special orthogonal group SO(3)\text{SO}(3), this function provides the corresponding linear endomorphism of the 3-dimensional Euclidean space R3\mathbb{R}^3. Specifically, it maps the 3×33 \times 3 matrix AA to its associated linear transformation T:R3R3T: \mathbb{R}^3 \to \mathbb{R}^3 relative to the standard basis.

theorem

11 is an eigenvalue of every ASO(3)A \in SO(3)

#one_is_eigenvalue

For every matrix AA in the special orthogonal group SO(3)SO(3), the linear endomorphism of R3\mathbb{R}^3 associated with AA has an eigenvalue equal to 11. Here, SO(3)SO(3) is the group of 3×33 \times 3 real matrices such that detA=1\det A = 1 and AA=IAA^\top = I.

theorem

Every ASO(3)A \in SO(3) has a stationary unit vector

#exists_stationary_vec

For every matrix AA in the special orthogonal group SO(3)SO(3), there exists a unit vector vR3v \in \mathbb{R}^3 such that vv is stationary under the action of AA, i.e., Av=vAv = v. Here, SO(3)SO(3) is the group of 3×33 \times 3 real matrices AA satisfying detA=1\det A = 1 and AA=IAA^\top = I.

theorem

Every ASO(3)A \in SO(3) fixes the first vector of some orthonormal basis

#exists_basis_preserved

For every matrix AA in the special orthogonal group SO(3)SO(3), there exists an orthonormal basis {v0,v1,v2}\{v_0, v_1, v_2\} of the 3-dimensional Euclidean space R3\mathbb{R}^3 such that the first basis vector v0v_0 remains invariant under the action of AA, i.e., Av0=v0Av_0 = v_0. Here, SO(3)SO(3) is the group of 3×33 \times 3 real matrices AA satisfying detA=1\det A = 1 and AA=IAA^\top = I.