Eulers PSI and PHI interchanged in Guide Std MMa Pkg

*To*: mathgroup at smc.vnet.net*Subject*: [mg3917] Eulers PSI and PHI interchanged in Guide Std MMa Pkg*From*: adbened at alumnae.caltech.edu ( Alto D. Benedicto)*Date*: Sun, 5 May 1996 23:14:08 -0400*Organization*: California Institute of Technology, Pasadena*Sender*: owner-wri-mathgroup at wolfram.com

Half a day ago, I posted the question: > Why is it that: Rotate3D[object3D, Pi/2, Pi/2, 0] doesn't show the > same picture as Rotate3D[Rotate3D[object3D, 0,Pi/2,0], Pi/2, 0, 0]? > It seems that the angle PHI doesn't behave according to the > definition on p.113 of Guide to Std Mma Pkg. As far as I > understand it, the definition of Rotate3D[obj, phi, theta psi] is > Rotate3D[Rotate3D[Rotate3D[obj,0,0,psi],0,theta,0],phi,0,0]. > (THETA and PSI are clockwise rotation wrt X and Z axis). For what it's worth, the parameters PHI and PSI are misprinted in p.113 of Guide to Std MMa Pkg for the commands Rotate3D and RotationMatrix3D. The correct form should be: RotationMatrix3D[psi, theta, phi] instead of RotationMatrix3D[phi, theta, psi]. Also, Rotate3D[psi, theta, phi] instead of Rotate3D[phi, theta, psi]. The standard definition of Euler angles follows, i.e., first rotate by angle psi about z, then angle theta about x, and finally angle phi about z again. (all rotations clockwise). Alto Benedicto adbened at aruba.ccit.arizona.edu ==== [MESSAGE SEPARATOR] ====