Procedure: thm_part_slice2d_fac Purpose: Helper function for thm_part_slice2d. Retrieves transformation matrix into field alligned coordinate systems. Input: probe: (string) spacecraft designation (e.g. 'a') coord: (string) target coordinates (e.g. 'phigeo') trange: (double) two element time range for slice mag_data: (string) name of tplot variable containing magnetic field data vectors: (float) N x 3 array of velocity vectors bfield: (float) magnetic field 3-vector vbulk: (float) bulk velocity 3-vector sunvec: (float) spacecraft-sun direction 3-vector Output: If 2d or 3d interpolation are being used then this will transform the velocity vectors and support vectors into the target coordinate system. The transformation matrix will be passed out via the MATRIX keyword. Notes: This assumes the transformation does not change substantially over the time range of the slice. $LastChangedBy: aaflores $ $LastChangedDate: 2014-07-31 11:16:59 -0700 (Thu, 31 Jul 2014) $ $LastChangedRevision: 15632 $ $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/spdsoft/trunk/projects/themis/spacecraft/particles/slices/thm_part_slice2d_fac.pro $