multiply and subtract in retain function

[CFF]

Hi

I have 1 variabel A. I need to create a new variabel B thats i created through the retain function. For the first observation must B must be equal to 1.

For all the other values B=1-B*A - where B is the retained result.

As an example:

Data have:

A:

0,5

0,5

0,5

Data want

A:       B

0,5     1

0,5     0,5 (calculated as: 1-1*0,5)

0,5     0,75 (calculated as: 1-0,5*0,5)

Best regards

[ballardw]

data want;

     set have;

     retain b 1;

     if _n_ > 1 then b= 1- b*a;

run;

[KrisNori]

DATA A10Aug2015_1;

  retain B 1;

  INPUT A;

  OUTPUT;

  B=1-B*A;

DATALINES;

0.5

0.5

0.5

;

[RW9]

I am not clear on what the dataset A is for, it doesn't add anything to the mix.  Adjust the do loop for number of iterations:

data want (drop=i);

  retain b 1;

  do i=1 to 5;

    b=1 - (b * 0.5);

    output;

  end;

run;