fiff_read_coord_trans

  usage: [trans_head2mri] = fiff_read_coord_trans(transfile)

  input:
       transfile = name of transformation fif file (usually stored in
       the subject's Freesurfer directory in /mri/T1-neuromag/sets).

  output:
       trans_head2mri = transformation structure from head to MRI coordinate systems.

                    Note: the inverse transformation, from MRI to head coordinate systems
                              can be obtained by just taking the inverse:
                                   trans_mri2head.from=5; trans_mri2head.to=4;
                                   trans_mri2head.trans=inv(trans_head2mri.trans);

  author:  Rey Ramirez  email: rrramir@uw.edu

0001 function [trans_head2mri] = fiff_read_coord_trans(transfile)
0002 %
0003 %  usage: [trans_head2mri] = fiff_read_coord_trans(transfile)
0004 %
0005 %  input:
0006 %       transfile = name of transformation fif file (usually stored in
0007 %       the subject's Freesurfer directory in /mri/T1-neuromag/sets).
0008 %
0009 %  output:
0010 %       trans_head2mri = transformation structure from head to MRI coordinate systems.
0011 %
0012 %                    Note: the inverse transformation, from MRI to head coordinate systems
0013 %                              can be obtained by just taking the inverse:
0014 %                                   trans_mri2head.from=5; trans_mri2head.to=4;
0015 %                                   trans_mri2head.trans=inv(trans_head2mri.trans);
0016 %
0017 %  author:  Rey Ramirez  email: rrramir@uw.edu
0018 
0019 FIFF = fiff_define_constants;
0020 [fid,~,dir] = fiff_open(transfile);
0021 a = find([dir.kind] == FIFF.FIFF_COORD_TRANS);
0022 pos = dir(a(1)).pos;
0023 tag = fiff_read_tag(fid,pos);
0024 trans_head2mri = tag.data;