eulerToRotationMatrix.m

% Create a 3x3 rotation matrix from Euler angles.
% Uses ZYX rotation order:
%   Rotation 1: psi about z
%   Rotation 2: theta about y
%   Rotation 3: phi about x
%
% R = eulerToRotationMatrix(phi,theta,psi)
%       Inputs:
%         phi:   rotation about x, radians
%         theta: rotation about y, radians
%         psi:   rotation about z, radians
%       Output:
%         R:     3x3 rotation matrix (i.e. direction cosine matrix)
%
% Example: For an aircraft using standard nomenclature 
%          (phi: roll, theta: pitch, psi: yaw), the resulting rotation
%          matrix expresses the rotation from a North-East-Down coordinate
%          frame to an aircraft body coordinate frame
%
%          R_ned2b = eulerToRotationMatrix(phi,theta,psi)
%
function R = eulerToRotationMatrix(phi,theta,psi)

    % Replace the following with appropriate code
    %R = eye(3);
    R_yaw = [cos(psi) sin(psi) 0; -sin(psi) cos(psi) 0; 0 0 1];
    R_pitch = [cos(theta) 0 -sin(theta); 0 1 0; sin(theta) 0 cos(theta)];
    R_roll = [1 0 0; 0 cos(phi) sin(phi); 0 -sin(phi) cos(phi)];
    R_yaw_to_pitch = R_pitch * R_yaw;
    R = R_roll * R_yaw_to_pitch;

end