subroutine smo(x,npts,y,nadd)
real x(npts)
real y(npts)
nh=nadd/2
do i=1+nh,npts-nh
sum=0.
do j=-nh,nh
sum=sum + x(i+j)
enddo
y(i)=sum
x=y
x(:nh)=0.
x(npts-nh+1:)=0.
return
end subroutine smo