1! 2! CalculiX - A 3-dimensional finite element program 3! Copyright (C) 1998-2021 Guido Dhondt 4! 5! This program is free software; you can redistribute it and/or 6! modify it under the terms of the GNU General Public License as 7! published by the Free Software Foundation(version 2); 8! 9! 10! This program is distributed in the hope that it will be useful, 11! but WITHOUT ANY WARRANTY; without even the implied warranty of 12! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13! GNU General Public License for more details. 14! 15! You should have received a copy of the GNU General Public License 16! along with this program; if not, write to the Free Software 17! Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 18! 19 subroutine rotationvectorinv(c,v) 20! 21! calculates rotation matrix from rotation vector 22! 23 implicit none 24! 25 real*8 c(3,3),v(3),theta,ds,dc 26! 27! 28! 29 theta=dsqrt(v(1)*v(1)+v(2)*v(2)+v(3)*v(3)) 30! 31 if (theta.eq.0.d0) then 32 c(1,1)=1.d0 33 c(1,2)=0.d0 34 c(1,3)=0.d0 35 c(2,1)=0.d0 36 c(2,2)=1.d0 37 c(2,3)=0.d0 38 c(3,1)=0.d0 39 c(3,2)=0.d0 40 c(3,3)=1.d0 41 else 42! 43 dc=dcos(theta) 44 ds=dsin(theta) 45! 46! C-matrix from Guido Dhondt, The Finite Element 47! Method for Three-Dimensional Thermomechanical 48! Applications p 158 49! 50 c(1,1)=dc+(1.d0-dc)*v(1)*v(1)/(theta*theta) 51 c(1,2)= (1.d0-dc)*v(1)*v(2)/(theta*theta)-ds*v(3)/theta 52 c(1,3)= (1.d0-dc)*v(1)*v(3)/(theta*theta)+ds*v(2)/theta 53 c(2,1)= (1.d0-dc)*v(2)*v(1)/(theta*theta)+ds*v(3)/theta 54 c(2,2)=dc+(1.d0-dc)*v(2)*v(2)/(theta*theta) 55 c(2,3)= (1.d0-dc)*v(2)*v(3)/(theta*theta)-ds*v(1)/theta 56 c(3,1)= (1.d0-dc)*v(3)*v(1)/(theta*theta)-ds*v(2)/theta 57 c(3,2)= (1.d0-dc)*v(3)*v(2)/(theta*theta)+ds*v(1)/theta 58 c(3,3)=dc+(1.d0-dc)*v(3)*v(3)/(theta*theta) 59 endif 60! 61 return 62! 63 end 64