PROGRAM pi
	IMPLICIT NONE
        INTEGER, PARAMETER :: nb_iter=100000000
        DOUBLE PRECISION :: pas, x, pi_approchee = 0.0D0, temps
        INTEGER :: i, t1, t2, ir

        pas  = 1.0D0 / nb_iter
        CALL SYSTEM_CLOCK(count=t1)

        DO i=1, nb_iter
                x = pas * (i - 0.5D0)
                pi_approchee = pi_approchee + 4.0D0 * pas / (1.0D0 + x * x)
        END DO

        CALL SYSTEM_CLOCK(count=t2, count_rate=ir)
        temps = REAL(t2 - t1) / ir
        PRINT '(" Valeur approchee de PI = ", F16.14)', pi_approchee
        PRINT '(" Temps d''execution : ", F7.3, " sec.")', temps
END PROGRAM pi