Program MONTECARLO_HIT_AND_MISS_3var
 		Implicit Double precision (A-H,o-z)
 		DOUBLE PRECISION g ,a,b,c,p,r,s ,u,v,pi
 		integer n , na
!
        a=0d0
        b=1d0
        c=1d0
        na=0
        n=10

             open(60,File="ejerc10aciertfallos3var.xls")
               call cpu_time(start)

                do j=n,10000000000

        	do 1 i=1,n
		u=rand()
		v=rand()
		z=rand()
		! definimos una nueva variable aleatoria
		w=rand()
                ! ahora g es funcion de 3 variables
	if (g(a+(b-a)*u,a+(b-a)*z,a+(b-a)*w).gt.c*v) na=na+1

1 	        continue
		p= real (na)/n
		r=(b-a)*c*p
		s=sqrt(p*(1.-p)/n)*c*(b-a)

                write(60,20)n,r,s
                if (n.gt.1d7) go to 30
                n=n*10
                na=0
                enddo
30              call cpu_time(finish)
                write(60,*)"Temps = ",finish-start ,"s"
                close(60)
20              Format(I20,4X,F20.14,4X,E20.14)
                end

                ! definimos la funcion a integrar
		Function g(x1,x2,x3)
                Implicit Double Precision (A-H,O-Z)
                g=exp(-x1**2-x2**2-x3**2)*cos(x2*x1+x3*x2+x3*x1)
                end