/* Henderson's 7-term Moving Average */
new; cls;
let data[50,1]=
      60
      61
      60
      62
      60
      63
      64
      65
      69
      70
      69
      66
      64
      64
      62
      64
      65
      55
      53
      57
      60
      58
      63
      63
      63
      68
      69
      69
      68
      69
      70
      67
      66
      67
      68
      69
      69
      77
      80
      80
      78
      76
      76
      72
      71
      70
      73
      71
      78
      80
;
data=rev(data);               /* original data in reverse order */
t=seqa(1,1,rows(data));

library pgraph;
graphset;
_pltype=6;
_plegctl=1;
_plegstr="actual\000Henderson 7";
title("Henderson 7");
xy(t,data~henderson7(data));







proc henderson7(x);
   local w,t,k,i,m,w1,w2,w3;
/* Symmetric part in the middle */
   w={0.412,0.294,0.059,-0.059};
   t=rows(x);
   k=rows(w)-1;
   w=rev(w[2:k+1])|w;
   m=zeros(rows(x),cols(x));
   i=k+1;
   do while i<=t-k;
      m[i,.]=w'x[i-k:i+k,.];
      i=i+1;
   endo;
/* Asymmetric part at end points */
   w1={-0.034,0.116,0.383,0.535}; 
   w2={-0.054,0.061,0.294,0.41,0.289};
   w3={-0.053,0.058,0.287,0.399,0.275,0.034};
   m[1,.]=rev(w1)'x[1:k+1,.]; m[t,.]=w1'x[t-k:t,.];
   m[2,.]=rev(w2)'x[1:k+2,.]; m[t-1,.]=w2'x[t-k-1:t,.];
   m[3,.]=rev(w3)'x[1:k+3,.]; m[t-2,.]=w3'x[t-k-2:t,.];
   retp(m);
endp;