! Solve for tension in support straps
! by doing static force balance
!  [e]*{T} = {0 0 W}^T
!  where e contains the direction cosines (unit vectors) of straps
!  ie sum of forces in x&y are 0., sum in z equals weight

use nag_mat_inv
character*16 arg

real*8, dimension(3,10) :: pts ! first six points are for laser, 7 is CG, 8,9,10 are straps
real*8, dimension(3,3) :: e ! coef matrix

 iarg=iargc()
 if(iarg.lt.1)stop " usage: tension.x zhook"
 narg = getarg(1,arg)
 read(arg,*) zhook

do
  read(*,*,iostat=istat) pts
  pts(3,7)=zhook
  if(istat.ne.0)exit
  do i=1,3
    do k=1,3
      e(k,i)=pts(k,7)-pts(k,i+7)
    enddo
  e(:,i)=e(:,i)/sqrt(dot_product(e(:,i),e(:,i)))
  enddo
  call nag_gen_mat_inv(e)
  write(*,"(3f12.6)") e(:,3)
enddo

stop
end