quat2dcm

Convert quaternion to direction cosine matrix

Syntax

n = quat2dcm(q)


Description

n = quat2dcm(q) calculates the direction cosine matrix, n, for a given quaternion, q. Input q is an m-by-4 matrix containing m quaternions. n returns a 3-by-3-by-m matrix of direction cosine matrices. The direction cosine matrix performs the coordinate transformation of a vector in inertial axes to a vector in body axes. Each element of q must be a real number.

Aerospace Toolbox uses quaternions that are defined using the scalar-first convention. This function normalizes all quaternion inputs.

Examples

Determine the direction cosine matrix from q = [1 0 1 0]:

dcm = quat2dcm([1 0 1 0])


dcm =

         0         0   -1.0000
         0    1.0000         0
    1.0000         0         0

Determine the direction cosine matrices from multiple quaternions:

q = [1 0 1 0; 1 0.5 0.3 0.1]; 
dcm = quat2dcm(q)


dcm(:,:,1) =

         0         0   -1.0000
         0    1.0000         0
    1.0000         0         0


dcm(:,:,2) =

    0.8519    0.3704   -0.3704
    0.0741    0.6148    0.7852
    0.5185   -0.6963    0.4963