src/matrix3.c file

Functions

auto mat3_identity(void) -> matrix3: Constructs the 3x3 identity matrix.
auto mat3_mul(matrix3 a, matrix3 b) -> matrix3: Multiplies two 3x3 matrices.
auto mat3_transpose(matrix3 m) -> matrix3: Computes the transpose of a 3x3 matrix.
auto mat3_inverse(matrix3 m) -> matrix3: Computes the inverse of a 3x3 matrix.
auto mat3_rotation_z(vm_float_t radians) -> matrix3: Constructs a 3x3 rotation matrix around the Z axis.
auto mat3_rotation_z_deg(vm_float_t degrees) -> matrix3: Constructs a 3x3 rotation matrix around the Z axis.
auto mat3_determinant(matrix3 m) -> vm_float_t: Computes the determinant of a 3x3 matrix.
auto mat3_mul_vec3(matrix3 m, vector3 v) -> vector3: Multiplies a 3x3 matrix by a vector3.
auto mat3_mul_vec2(matrix3 m, vector2 v) -> vector2: Applies a 3x3 affine transform to a vector2.
auto mat3_rotation_x(vm_float_t radians) -> matrix3: Constructs a 3x3 rotation matrix around the X axis.
auto mat3_rotation_x_deg(vm_float_t degrees) -> matrix3: Constructs a 3x3 rotation matrix around the X axis.
auto mat3_rotation_y(vm_float_t radians) -> matrix3: Constructs a 3x3 rotation matrix around the Y axis.
auto mat3_rotation_y_deg(vm_float_t degrees) -> matrix3: 3x3 rotation about Y from an angle in degrees.
auto mat3_translate(vector2 t) -> matrix3: Builds a 3x3 2D translation matrix.
auto mat3_scale(vector2 s) -> matrix3: Builds a 3x3 2D scaling matrix.
auto mat3_from_mat4(matrix4 m) -> matrix3: Copies the upper-left 3x3 of a matrix4.
auto mat3_normal(matrix3 m) -> matrix3: Inverse-transpose of a 3x3 (normal matrix).
auto mat3_sym_eigen(matrix3 m, matrix3* axes) -> vector3: Analytical eigenvalues of a symmetric 3×3, sorted ascending.

Function documentation

matrix3 mat3_identity(void)

Constructs the 3x3 identity matrix.

Returns	The identity matrix3.

matrix3 mat3_mul(matrix3 a, matrix3 b)

Multiplies two 3x3 matrices.

Parameters
a	The first matrix.
b	The second matrix.
Returns	The product matrix.

Column-major product AB so (AB)v == A(Bv) (column vector on the right).

matrix3 mat3_transpose(matrix3 m)

Computes the transpose of a 3x3 matrix.

Parameters
m	The input matrix.
Returns	The transposed matrix.

matrix3 mat3_inverse(matrix3 m)

Computes the inverse of a 3x3 matrix.

Parameters
m	The input matrix.
Returns	The inverse matrix.

On a singular matrix the result is identity.

matrix3 mat3_rotation_z(vm_float_t radians)

Constructs a 3x3 rotation matrix around the Z axis.

Parameters
radians	Rotation angle in radians.
Returns	The rotation matrix3.

matrix3 mat3_rotation_z_deg(vm_float_t degrees)

Constructs a 3x3 rotation matrix around the Z axis.

Parameters
degrees	The rotation angle in degrees.
Returns	The resulting rotation matrix3.

The angle is given in degrees and internally converted to radians.

vm_float_t mat3_determinant(matrix3 m)

Computes the determinant of a 3x3 matrix.

Parameters
m	The input matrix.
Returns	The determinant value.

vector3 mat3_mul_vec3(matrix3 m, vector3 v)

Multiplies a 3x3 matrix by a vector3.

Parameters
m	Input matrix.
v	Input vector.
Returns	The resulting vector3.

vector2 mat3_mul_vec2(matrix3 m, vector2 v)

Applies a 3x3 affine transform to a vector2.

Parameters
m	Input matrix.
v	Input vector.
Returns	The resulting vector2.

matrix3 mat3_rotation_x(vm_float_t radians)

Constructs a 3x3 rotation matrix around the X axis.

Parameters
radians	Rotation angle in radians.
Returns	The rotation matrix3.

matrix3 mat3_rotation_x_deg(vm_float_t degrees)

Constructs a 3x3 rotation matrix around the X axis.

Parameters
degrees	The rotation angle in degrees.
Returns	The rotation matrix3.

The angle is provided in degrees and converted to radians internally.

matrix3 mat3_rotation_y(vm_float_t radians)

Constructs a 3x3 rotation matrix around the Y axis.

Parameters
radians	The rotation angle in radians.
Returns	The rotation matrix3.

matrix3 mat3_rotation_y_deg(vm_float_t degrees)

3x3 rotation about Y from an angle in degrees.

Parameters
degrees	Rotation angle in degrees.
Returns	Rotation matrix3.

matrix3 mat3_translate(vector2 t)

Builds a 3x3 2D translation matrix.

Parameters
t	Translation vector.
Returns	The resulting matrix3.

matrix3 mat3_scale(vector2 s)

Builds a 3x3 2D scaling matrix.

Parameters
s	Scale vector.
Returns	The resulting matrix3.

matrix3 mat3_from_mat4(matrix4 m)

Copies the upper-left 3x3 of a matrix4.

Parameters
m	Input matrix.
Returns	The resulting matrix3.

matrix3 mat3_normal(matrix3 m)

Inverse-transpose of a 3x3 (normal matrix).

Parameters
m	Linear part of a model transform.
Returns	The normal matrix3.

vector3 mat3_sym_eigen(matrix3 m, matrix3* axes)

Analytical eigenvalues of a symmetric 3×3, sorted ascending.

Parameters
m	Input matrix (symmetrized internally).
axes	Optional; receives eigenvector columns. May be NULL.
Returns	Eigenvalues as a vector3, sorted ascending.

m is symmetrized as (A+Aᵀ)/2. Eigenvalues are sorted ascending. Eigenvectors are the columns of axes when non-NULL (axes * diag(moments) * axesᵀ ~= m). Analytical closed form; not routed through heap SVD or Jacobi.