%euler angles to quaternions for the aerospace sequence


function [q0,q1,q2,q3]=euler_to_quat(phi,theta,psi)



x=phi/2; y=theta/2; z=psi/2;

q0=cos(z)*cos(y)*cos(x)+sin(z)*sin(y)*sin(x);
q1=cos(z)*cos(y)*sin(x)-sin(z)*sin(y)*cos(x);
q2=cos(z)*sin(y)*cos(x)+sin(z)*cos(y)*sin(x);
q3=sin(z)*cos(y)*cos(x)-cos(z)*sin(y)*sin(x);

if abs(q0)<10^-10
    q0=0;
end


if abs(q1)<10^-10
    q0=0;
end

if abs(q2)<10^-10
    q0=0;
end

if abs(q3)<10^-10
    q0=0;
end
    

end