interation (previous line)

[Augusto]

Hello,

I need to create a data set like that bellow.

where variable "a" need to be the value of the previous value of the variable "c" and so on.

b = a * anual/12; 

safra	a	b	c	anual
1	45.483.247.875	0	45.483.247.875	2,97%
2	45.483.247.875	112.571.038	45.370.676.837	2,97%
3	45.370.676.837	112.292.425	45.258.384.411	2,97%
4	45.258.384.411	112.014.501	45.146.369.910	2,97%
5	45.146.369.910	111.737.266	45.034.632.644	2,97%

Thanks

[Astounding]

Getting A is straightforward:

data want;

set have;

a = lag(c);

if _n_=1 then a=c;

run;

Getting B a value of 0 can also be done (but requires a little more coding), if you are computing B as part of this step.  It might depend on what is in ANNUAL.  Is it character, with a value of "2.97%" or is it numeric with a value of 0.297?