3.0.0

Added

• Add Mat22 for 2x2 matrix arithmetic, inversion, trace, determinant, and 2D linear transforms.
• Add Vec4 arithmetic and explicit homogeneous point (w = 1) and direction (w = 0) constructors.
• Add trace/1, determinant/1, submatrix/3, and cofactor/3 to Mat33 and Mat44.
• Add Mat33.orthonormalize/1 for row bases, preserving handedness and rejecting degenerate inputs.
• Add reflection and shear constructors to Mat22, Mat33, and Mat44. Mat33 names explicitly distinguish 2D affine transforms from 3D linear transforms.
• Add Mat44.orient/3, look_at/3, make_billboard/3, and make_billboard_axis/3 with right-handed, -Z-forward camera conventions.
• Add Mat44.perspective/4 and ortho/6 with normalized device depth in [-1, +1]. Perspective projection requires an explicit divide by the resulting homogeneous coordinate.
• Add Benchee benchmarks for Vec2, Vec3, Mat33, Mat44, and Quatern operations.
• Add an Octave cross-check harness under bench/octave that verifies every public function against independent reference math.
• Expand numeric, boundary, random, and transform tests, and enforce 100% library line coverage in CI.

Changed

• Move CI to GitHub Actions and remove CircleCI configuration and reporting.
• Document matrix storage, row-vector graphics transforms, composition order, quaternion components, and world-space angular velocity for quaternion integration.
• Convert integer components to floats in Vec3.create/1 and Quatern.from_list/1, matching their documented representation.

Fixed

• Correct quaternion-to-matrix conversions to produce row-vector rotation matrices consistent with the matrix transform helpers.
• Correct Quatern.from_rotation_matrix/1 rotation direction, diagonal selection, and {w, x, y, z} component order, including rotations with nonpositive trace.
• Correct Mat44.make_rotate_y/1 to agree with right-handed vector and quaternion rotations.
• Make Quatern.slerp/3 follow the shortest arc and handle opposite-sign representations of the same orientation without producing the zero quaternion.
• Make Vec2.length_manhattan/1 and Vec3.length_manhattan/1 sum absolute component values.
• Correct the August 2024 changelog heading to identify the published 2.6.0 release.

Upgrading from 2.x

• Update the dependency requirement to {:graphmath, "~> 3.0.0"}. The minimum Elixir requirement remains ~> 1.15.
• Review workarounds for rotation direction. Quatern.to_rotation_matrix_33/1 and to_rotation_matrix_44/1 now return the transpose of their previous results; Quatern.from_rotation_matrix/1 expects the corresponding row-vector convention. Use Mat33.apply_left/2 for full 3D row vectors or the Mat44 point/vector transform helpers. apply/2 still computes a column-vector product.
• Remove any angle negation used to compensate for Mat44.make_rotate_y/1. A positive quarter-turn about Y now transforms +X toward -Z.
• Treat quaternion interpolation endpoints as orientations. Quatern.slerp/3 can return the negation of the second quaternion at t = 1 to select the shortest arc. Use Quatern.equal/2 or equal/3 for orientation comparisons.
• Expect nonnegative Manhattan lengths for vectors with negative components. For example, Vec2.length_manhattan({-3.0, 4.0}) now returns 7.0.
• Update integer-specific pattern matches or strict equality checks on results of Vec3.create/1 and Quatern.from_list/1: these constructors now return floats for integer inputs.