a=a*lag(a) How could I realize this function?

shiyiming

I have tried:
a=a*lag(a);
But it seems not working.

I want make the variables multiply continuous.


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2
...
I want it to be
1
3
12
24
...

shiyiming

when _n_=1, lag(a) seems to be missing value.

then could add one extra condition to exclude this case occurance like when _n_ ge 1 then a*lag(a).

Try it. hope it could work!   <!-- s:lol: --><img src="{SMILIES_PATH}/icon_lol.gif" alt=":lol:" title="Laughing" /><!-- s:lol: -->

shiyiming

试过了，不行。

谁能帮忙写个代码把这个算一下？

1
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4
。。。

1
2
6
24
。。。

shiyiming

[code:8dded]data ahuige;
  input a;
  retain s 1;
  s=s*a;
  cards;
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2
;
run;[/code:8dded]

shiyiming

%let n=2;
data mutiply (drop=s);
  retain s;
  set test;
  s = sum(s,log(x), -log(lag&n(x))) ;
  moving_product=exp(s);
run;

proc print;
run;

shiyiming

多谢各位。