On Thu, Jul 28, 2011 at 21:48, Robert Love <rblove_li...@comcast.net> wrote: > > On Jul 28, 2011, at 7:42 AM, Martin Ling wrote: > >> On Wed, Jul 27, 2011 at 10:29:08PM -0500, Robert Love wrote: >>> >>> To use quaternions I find I often need conversion to/from matrices and >>> to/from Euler angles. Will you add that functionality? >> >> Yes, I intend to. Note that these conversions are already available in >> the standalone (non-dtype) implementation in imusim.maths.quaternions: >> >> http://www.imusim.org/docs/api/imusim.maths.quaternions.Quaternion-class.html#setFromEuler >> http://www.imusim.org/docs/api/imusim.maths.quaternions.Quaternion-class.html#toEuler >> http://www.imusim.org/docs/api/imusim.maths.quaternions.Quaternion-class.html#setFromMatrix >> http://www.imusim.org/docs/api/imusim.maths.quaternions.Quaternion-class.html#toMatrix >> >> I should do a new release though - the Euler methods there only support >> ZYX and ZXY order conversions, my development version supports any order. >> >>> Will you handle the left versor and right versor versions? >> >> I don't know what this means. Please enlighten me and I'll be happy to >> try! I thought a 'right versor' was a unit quaternion representing an >> angle of 90 degrees (as in 'right angle') - I don't see what a 'left' >> one would be. >> > > Quaternions have a "handedness" or a sign convention. The recently departed > Space Shuttle used a Left versor convention while most things, including > Space Station, use the right versor convention, in their flight software. > Made for frequent confusion.
For what it's worth, I have found this paper by James Diebel to be the most complete listing of all of the different conventions and conversions amongst quaternions, Euler angles, and rotation vectors: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.110.5134 -- Robert Kern "I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion