easytensor-0.3.2.0: Pure, type-indexed haskell vector, matrix, and tensor library.

Numeric.Quaternion

Description

Quaternion operations implemented for Floats and Doubles.

The types QDouble and QFloat have the same representation as corresponding Vector t 4. This means, you can do a cheap conversion between the types.

However, arithmetic instances, such as Num and Floating are implemented in substentially different ways. For example, fromInteger fills a vector fully but sets only real part to a quaternion:

>>> 1 = vec4 1 1 1 1
>>> 1 = packQ 0 0 0 1


All other numeric operations for vectors are element-wise, but for quaternions I have implemented the actual quaternion math. Some of the operations (such as trigonometric operations) are ambiguous for quaternions; the general rules I follow:

1. Preserve imaginary vector axis same if possible;
2. If both +q and -q are possible, prefer real value positive (re q >= 0).

Synopsis

# Documentation

class Quaternion t where Source #

Quaternion operations

Minimal complete definition

Associated Types

data Quater t Source #

Quaternion data type. The ordering of coordinates is x y z w, where w is an argument, and x y z are components of a 3D vector

Methods

packQ :: t -> t -> t -> t -> Quater t Source #

Set the quaternion in format (x,y,z,w)

unpackQ :: Quater t -> (t, t, t, t) Source #

Get the values of the quaternion in format (x,y,z,w)

fromVecNum :: Vector t 3 -> t -> Quater t Source #

Set the quaternion from 3D axis vector and argument

fromVec4 :: Vector t 4 -> Quater t Source #

Set the quaternion from 4D vector in format (x,y,z,w)

toVec4 :: Quater t -> Vector t 4 Source #

Transform the quaternion to 4D vector in format (x,y,z,w)

square :: Quater t -> t Source #

Get scalar square of the quaternion.

> realToFrac (square q) == q * conjugate q

im :: Quater t -> Quater t Source #

Imagine part of quaternion (orientation vector)

re :: Quater t -> Quater t Source #

Real part of the quaternion

imVec :: Quater t -> Vector t 3 Source #

Get imagenery 3D vector of the quaternion

taker :: Quater t -> t Source #

Real part of the quaternion into number

takei :: Quater t -> t Source #

i-th component

takej :: Quater t -> t Source #

j-th component

takek :: Quater t -> t Source #

k-th component

conjugate :: Quater t -> Quater t Source #

Conjugate quaternion (negate imaginary part)

rotScale :: Quater t -> Vector t 3 -> Vector t 3 Source #

Rotates and scales vector in 3D using quaternion. Let q = (cos (a/2), sin (a/2) * v); then the rotation angle is a, and the axis of rotation is v. Scaling is proportional to |v|^2.

>>> rotScale q x == q * x * (conjugate q)


getRotScale :: Vector t 3 -> Vector t 3 -> Quater t Source #

Creates a quaternion q from two vectors a and b. rotScale q a == b

axisRotation :: Vector t 3 -> t -> Quater t Source #

Creates a rotation versor from an axis vector and an angle in radians. Result is always a unit quaternion (versor). If the argument vector is zero, then result is a real unit quaternion.

qArg :: Quater t -> t Source #

Quaternion rotation angle

>>> q /= 0 ==> axisRotation (imVec q) (qArg q) == signum q


fromMatrix33 :: Matrix t 3 3 -> Quater t Source #

Create a quaternion from a rotation matrix. Note, that rotations of q and -q are equivalent, there result of this function may be ambiguious. I decided to force its real part be positive:

>>> taker (fromMatrix33 m) >= 0


fromMatrix44 :: Matrix t 4 4 -> Quater t Source #

Create a quaternion from a homogenious coordinates trasform matrix. Ignores matrix translation transform. Note, that rotations of q and -q are equivalent, there result of this function may be ambiguious. I decided to force its real part be positive:

>>> taker (fromMatrix44 m) >= 0


toMatrix33 :: Quater t -> Matrix t 3 3 Source #

Create a rotation matrix from a quaternion. Note, that rotations of q and -q are equivalent, so the following property holds:

>>> toMatrix33 q == toMatrix33 (-q)


toMatrix44 :: Quater t -> Matrix t 4 4 Source #

Create a homogenious coordinates trasform matrix from a quaternion. Translation of the output matrix is zero. Note, that rotations of q and -q are equivalent, so the following property holds:

>>> toMatrix44 q == toMatrix44 (-q)