Cummulative multiplication

[Ronein]

Hello
I am trying to perform cumulative multilplication calculation between rows.
Data tbl.
Input p:
Cards:
0.99
0.97
0.95
;
Ron;

Data tbl2;
Set tbl1;
Retain cum_p,
If first.p then cum_p=p;
Else cum_p=cum_p*p;
Run;

[RichardDeVen]

Change the logic

if first.p

to

if _N_ = 1

You have a couple typo errors  (dot, colon, comma) where semi-colons should be, so I guess the code is untested. 

[ed_sas_member]

Hi @Ronein 

You cannot use first.p as you have not defined p as a group variable in a BY statement.

See the log:

 NOTE: Variable first.p is uninitialized.

Please try "if _n_=1 then ..." instead:

Data tbl2;
Set tbl1;
Retain cum_p;
If _n_=1 then cum_p=p;
Else cum_p=cum_p*p;
Run;

Best,

[Kurt_Bremser]

Testing data step code for example data is not a crime, it is a necessity and a sign of good manners.

You can have it much easier by initializing the retained variable to 1:

data have;
input p;
cards;
0.99
0.97
0.95
;

data want;
set have;
retain cum_p 1;
cum_p = cum_p * p;
run;