!**********************************************
!* Geatest common divisor and Smallest common *
!*     multiple of several integer numbers    *
!* ------------------------------------------ *
!* Ref.: "Mathematiques en Turbo-Pascal by    *
!*        M. Ducamp and A. Reverchon (2),     *
!*        Eyrolles, Paris, 1988".             *
!* ------------------------------------------ *
!* Sample run:                                *
!*                                            *
!* GCD and SCM of integer numbers:            *
!*                                            *
!* First number: 9936                         *
!* Next number : 414                          *
!* Next number : 3174                         *
!* Next number : 0                            *
!*                                            *
!* GCD =        138.                          *
!* SCM =     228528.                          *
!*                                            *
!*                 F90 Version By J-P Moreau  *
!*                     (www.jpmoreau.fr)      *
!**********************************************
program Test_gcd
  
  implicit none
  real*4 pg, pp, x, xx, GCD
  print *,' '
  print *,'GCD and SCM of integer numbers:'
  print *,' '
  write(*,100,advance='no'); read *, pg
  pp=pg
10 write(*,110,advance='no'); read *, x
  xx=x
  if (x>0.) then
    pg=GCD(pg,xx)
	xx=x
    pp=pp*xx/GCD(pp,xx)
  end if
  if(abs(x)<1e-10) goto 20
  goto 10
20 print *,' '
  write(*,200)  pg
  write(*,210)  pp
  print *,' '
  stop
100 format(' First number : ')
110 format(' Next number  : ')
200 format(' GCD = ',F12.0)
210 format(' SCM = ',F12.0)
end

real*4 FUNCTION GCD(a,b)
  implicit none
  real*4 a, b, r, temp
  a = int(abs(a))
  b = int(abs(b))
  if (a>1e10.or.b>1e10) then 
    GCD=1; return
  endif
  if (a.eq.0.or.b.eq.0) then 
    GCD=1; return
  endif
  if (a<b) then
    temp=a; a=b; b=temp
  endif

1010 r=a-b*int(a/b)
    a=b; b=r
  if (abs(r)>1e-10) goto 1010
  GCD = a
return
end

! end of file gcd.f90