diff --git a/lib/smo.f90 b/lib/smo.f90
new file mode 100644
index 000000000..94a337848
--- /dev/null
+++ b/lib/smo.f90
@@ -0,0 +1,23 @@
+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
+  enddo
+  y(:nh)=0.
+  y(npts-nh+1:)=0.
+
+  fac=1.0/nadd
+  do i=1,npts
+     x(i)=fac*y(i)
+  enddo
+
+  return
+end subroutine smo