matlab function to convert quaternion to euler angles

quat2euler.m

function [phi_,theta_,psi_] = quat2euler(measurement_)
qw = measurement_.quat_w;
qx = measurement_.quat_x;
qy = measurement_.quat_y;
qz = measurement_.quat_z;

% roll - phi
sinr = 2 * (qw .* qx + qy .* qz);
cosr = 1 - 2 * (qx.^2 + qy.^2);
phi_ = atan2(sinr,cosr);

% pitch - theta
sinp = asin(2 * (qw .* qy - qz .* qx));

%if (sinp > 1.0)
%    sinp = 1.0;
%elseif (sinp < -1.0)
%    sinp = -1.0;
%end

theta_ = asin(sinp);

% yaw - psi
siny = 2 * (qw .* qz + qx .* qy);
cosy = 1 - 2 * (qy.^2 + qz.^2);

psi_ = atan2(siny,cosy);

end