ESyS-Particle

quaternion in QuaternionPy.cpp

Asked by Jiadun Liu

Dear All,

I'm confused about the quaternion defined in QuaternionPy.cpp

 QuaternionPy::QuaternionPy(
      double q0,
      double q1,
      double q2,
      double q3
    ) : Quaternion(q0, Vec3(q1, q2, q3))
    {
    }

    QuaternionPy::QuaternionPy(const Vec3Py &v)
      : Quaternion(
          cos(v.norm()/2.0),
          v*(sin(v.norm()/2.0)/v.norm())
        )
    {
    }

Is v.norm() the rotation angle?

Why not Quaternion( cos(q0/2.0),sin(q0/2.0)*Vec3(q1,q2,q3))?

Best regards,
Jiadun

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Jiadun Liu (liujiadun) said : 		#1

Dear all,

Finally, I undstand that there are two ways to identify the parameters for quaternion.

Best regards,
Jiadun