Date:         Thu, 10 Nov 2005 07:34:41 -0800
Reply-To:     newuser <chenlse@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         newuser <chenlse@GMAIL.COM>
Organization: http://groups.google.com
Subject:      macro questions
Comments: To: sas-l@uga.edu
Content-Type: text/plain; charset="iso-8859-1"

Hi, everyone,I have a problem writing macro program.
I have data with two variables: date and price.

I want to multiply all the "price" observations from after the 'drop
time' by 2 when there is  a big drop in it compared to the last
observation.
for example, the raw data is:
date         price
10-12-1992   13
10-13-1992   13
10-14-1992   13
10-15-1992   6
10-16-1992   7
10-17-1992   7
10-18-1992   3
10-19-1992   3

And I want to get:

10-12-1992   13
10-13-1992   13
10-14-1992   13
10-15-1992   12
10-16-1992   14
10-17-1992   14
10-18-1992   12
10-19-1992   12

but it is not working properly. Below is my program:


/* below, I record the number of times of 'big drop' in price
   and the happening time  */

data _null_;
   set temp;
   retain lp i( 0 0);
   if price<lp then do;
    i=i+1;
    call symput('sd'||left(i),date);
        call symput('sn',put(i));
        end;
lp=price;
run;

%global mj;
%let mj=0;

%macro loop(cdate=);
%let mj=0;
%do v=1 %to &sn;
%if &cdate>=&&sd&v %then %let mj=&v;
%end;

%mend;


data temp_1;
   set temp;
%loop(cdate=date);
price=price*(2**(&mj));

run;


Thank you!!

chen