Program MONTECARLO_MUESTREO_UNIFORME_3var
 		Implicit Double precision (A-H,o-z)
 		DOUBLE PRECISION g,g0,a,b,r1,s1,r,s,pi,u,z
 		real finish ,start
 		integer n

        a=0d0
        b=1d0
        n=10
             open(60,File="ejerc10mostrunif3var.xls")

                 call cpu_time(start)


                do j=n,10000000000

                r1=0.
                s1=0.
                do 1 i=1,n
                u=rand()
                v=rand()
                z=rand()
                g0=g(a+(b-a)*u,a+(b-a)*v,a+(b-a)*z)
                r1=r1+g0
                s1=s1+g0*g0
1               continue
                r1=r1/n
                s1=sqrt((s1/n-r1*r1)/n)
                r=(b-a)*r1
                s=(b-a)*s1
                write(60,20)n,r,s
                if (n.gt.1d7) go to 30
                n=n*10
                enddo

30                call cpu_time(finish)
                write(60,*)"Temps = ",finish-start ,"s"
                close(60)
20              Format(I20,4X,F20.14,4X,E20.14)

                end

		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