1! 2! CalculiX - A 3-dimensional finite element program 3! Copyright (C) 1998 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 planeeq(cotet,nodef,planfal) 20! 21! calculate the equation of a plane through the points nodef(1), 22! nodef(2) and nodef(3). The equation of the plane is 23! planfal(1)*x+planfal(2)*y+planfal(3)*z+planfal(4)=0; the 24! coordinates of the nodes are stored in cotet 25! 26! the vector (planefal(1),planfal(2),planfal(3)) is orthogonal 27! to the plane and is normalized 28! 29 implicit none 30! 31 integer nodef(3) 32 real*8 cotet(3,*),planfal(4),x1,y1,z1,x2,y2,z2,dd 33! 34 x1=cotet(1,nodef(1))-cotet(1,nodef(2)) 35 y1=cotet(2,nodef(1))-cotet(2,nodef(2)) 36 z1=cotet(3,nodef(1))-cotet(3,nodef(2)) 37! 38 x2=cotet(1,nodef(1))-cotet(1,nodef(3)) 39 y2=cotet(2,nodef(1))-cotet(2,nodef(3)) 40 z2=cotet(3,nodef(1))-cotet(3,nodef(3)) 41! 42 planfal(1)=y1*z2-y2*z1 43 planfal(2)=x2*z1-x1*z2 44 planfal(3)=x1*y2-x2*y1 45! 46 dd=dsqrt(planfal(1)*planfal(1)+planfal(2)*planfal(2)+ 47 & planfal(3)*planfal(3)) 48! 49 if(dd.lt.1.d-10) then 50 planfal(1)=0.d0 51 planfal(2)=0.d0 52 planfal(3)=0.d0 53 planfal(4)=0.d0 54 return 55 endif 56! 57 planfal(1)=planfal(1)/dd 58 planfal(2)=planfal(2)/dd 59 planfal(3)=planfal(3)/dd 60! 61 planfal(4)=-(planfal(1)*cotet(1,nodef(1))+ 62 & planfal(2)*cotet(2,nodef(1))+ 63 & planfal(3)*cotet(3,nodef(1))) 64! 65 return 66 end 67 68