1 | c$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
   2 | c$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
   3 | c$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
   4 | c$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
   5 | c
   6 | c.......................................................................
   7 | c
   8 | c  random generator from a chi-square distribution
   9 | c
  10 | c  out : * $x$        ---> xchra
  11 | c
  12 | c.......................................................................
  13 |       subroutine chra(xchra)
  14 | c.......................................................................
  15 |       implicit double precision (a-h,o-z)
  16 | c.......................................................................
  17 |       parameter (pichra=3.141592654d0)
  18 | c.......................................................................
  19 |       call rand_uniforme(chra1)
  20 |       call rand_uniforme(chra2)
  21 |       xchra=-2.d0*dlog(chra1)*dsin(pichra/2.d0*chra2)**2
  22 | c.......................................................................
  23 |       return
  24 |       end