program quadratic
! solve a quadratic with real roots
! JWP 22/10/98

implicit none

real :: a, b, c, d, x, x1, x2
!
a = 1
b = 2
c = -3
!
print *, 'Solving quadratic:'
print *, a, ' x**2 +', b, ' x + ', c
! check nature of roots..
!
d = b**2 - 4.0*a*c
!
if (d<0) then
   print *, 'Has complex roots.'
else
   x1 = (-b + sqrt(d)) / 2.0 / a
   x2 = (-b - sqrt(d)) / 2.0 / a
   print *, 'Roots are:', x1, x2
end if
!
end program quadratic