Program 3.1. 이차 방정식

PROGRAM QuadraticEquations_1
!---------------------------------------------------------------------------------
!	Program to solve a quadratic equation using the quadratic formula.
!
!	Variables used are:
!		A, B, C				: the coefficients of the quadratic equation
!		Discriminant		: the discriminant, B**2 - 4.0*A*C
!		Root_1, Root_2	: the two roots of the equation
!
!	Input		: The coefficients A, B, and C
!	Output	: The two roots of the equation or the (negative) discriminant
!				and a message indicating that there are no real roots
!---------------------------------------------------------------------------------

	IMPLICIT NONE

	REAL A, B, C, Discriminant, Root_1, Root_2
	
	! Get he coefficients
	PRINT *, "Enter the coefficients of the quadratic equation:"
	READ *, A, B, C
	
	! Calculate the coefficients
	Discriminant = B**2 - 4.0*A*C
	
	! Check if discriminant is nonnegative. If it is, calculate and
	! display the roots. Otherwise display the value of the discriminant
	! and a no-real-roots message.
	IF (Discriminant >= 0) THEN
		Discriminant = SQRT(Discriminant)
		Root_1 = (-B + Discriminant) / (2.0 * A)
		Root_2 = (-B - Discriminant) / (2.0 * A)
		PRINT *, "The roots are", Root_1, Root_2
	ELSE
		PRINT *, "Discriminant is", Discriminant
		PRINT *, "There are no real roots"
	END IF
	
	pause
End PROGRAM QuadraticEquations_1