On Apr 26, 2013, at 5:30 AM, Kun-Dar Li <kun...@mail.nutn.edu.tw> wrote:
> I use two different methods to define the > orientation as the following: > theta=arctan2(phi.getFaceGrad()[1], phi.getFaceGrad()[0]) > theta=arctan(phi.getFaceGrad()[1] / phi.getFaceGrad()[0]) > However, I got a slight different result from above. Please define "slight difference". > Can someone tell me > what's the difference between these two methods? Which one is more correct > to define the theta? These routines are documented at: http://docs.scipy.org/doc/numpy/reference/generated/numpy.arctan.htm http://docs.scipy.org/doc/numpy/reference/generated/numpy.arctan2.htm arctan2 is the appropriate function to use. > And, when I put the theta into the equation of psi=1+0.5cos(4*theta) to > calcalute the my anisotropy system , it is expected there is a fourfold > symmetry. Unforturnately, only threefold symmetry is appeared. If I try > 1+0.5cos(5*theta), only fourfold symmetry is shown. What example are you looking at? This is not the symmetry expression from http://www.ctcms.nist.gov/fipy/examples/phase/generated/examples.phase.anisotropy.html. _______________________________________________ fipy mailing list fipy@nist.gov http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
