1## Copyright (C) 2002 Etienne Grossmann <etienne@egdn.net> 2## 3## This program is free software; you can redistribute it and/or modify it under 4## the terms of the GNU General Public License as published by the Free Software 5## Foundation; either version 3 of the License, or (at your option) any later 6## version. 7## 8## This program is distributed in the hope that it will be useful, but WITHOUT 9## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more 11## details. 12## 13## You should have received a copy of the GNU General Public License along with 14## this program; if not, see <http://www.gnu.org/licenses/>. 15 16## -*- texinfo -*- 17## @deftypefn{Function File} {[@var{vstacked}, @var{astacked}] =} rotparams (@var{rstacked}) 18## @cindex 19## The function w = rotparams (r) - Inverse to rotv(). 20## Using, @var{w} = rotparams(@var{r}) is such that 21## rotv(w)*r' == eye(3). 22## 23## If used as, [v,a]=rotparams(r) , idem, with v (1 x 3) s.t. w == a*v. 24## 25## 0 <= norm(w)==a <= pi 26## 27## :-O !! Does not check if 'r' is a rotation matrix. 28## 29## Ignores matrices with zero rows or with NaNs. (returns 0 for them) 30## 31## @seealso{rotv} 32## @end deftypefn 33 34function [vstacked, astacked] = rotparams (rstacked) 35 36 N = size (rstacked,1) / 3; 37 38 ## ang = 0 ; 39 ## if length(varargin), 40 ## if strcmp(varargin{1},'ang'), ang = 1; end 41 ## end 42 ok = all ( ! isnan (rstacked') ) & any ( rstacked' ); 43 ok = min ( reshape (ok,3,N) ); 44 ok = find (ok) ; 45 ## keyboard 46 vstacked = zeros (N,3); 47 astacked = zeros (N,1); 48 for j = ok, 49 r = rstacked(3*j-2:3*j,:); 50 [v,f] = eig (r); 51 f = diag(f); 52 53 [m,i] = min (abs (real (f)-1)); 54 v = v(:,i); 55 56 w = null (v'); 57 u = w(:,1); 58 a = u'*r*u; 59 if a<1, 60 a = real (acos (u'*r*u)); 61 else 62 a = 0; 63 endif 64 ## Check orientation 65 x=r*u; 66 if v'*[0 -u(3) u(2); u(3) 0 -u(1);-u(2) u(1) 0]*x < 0, v=-v; endif 67 68 69 if nargout <= 1, v = v*a; endif 70 vstacked(j,:) = -v'; 71 astacked(j) = a; 72 endfor 73endfunction 74