Explanation:
PROGRAM QuadraticEquation
IMPLICIT NONE
REAL :: a, b, c
REAL :: d
REAL :: root1, root2
! read in the coefficients a, b and c
READ(*,*) a, b, c
WRITE(*,*) 'a = ', a
WRITE(*,*) 'b = ', b
WRITE(*,*) 'c = ', c
WRITE(*,*)
! compute the square root of discriminant d
d = b*b - 4.0*a*c
IF (d >= 0.0) THEN
d = SQRT(d)
root1 = (-b + d)/(2.0*a)
root2 = (-b - d)/(2.0*a)
WRITE(*,*) 'Roots are ', root1, ' and ', root2
ELSE
WRITE(*,*) 'no real roots exist!'
WRITE(*,*) 'Discriminant = ', d
END IF
END PROGRAM QuadraticEquation
