关于sas语法问题疑问？

shiyiming

我是sas初学者，别人给我写了一个sas程序，但是里面我只懂sas基本语法，稍微复杂的就不懂了。下面是程序，谁能帮我解释一下，关键是百分号是什么意思，还有macro,call symput,是什么意思啊，或者谁有关于这方面的详细的资料啊？麻烦穿给我吧，我的mail:atomdust@163.com，有点急，多谢了！
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%macro product(aa=,bb=);
proc sql;
create table c as
select intercept as intercept, x1*y1 as z1 %do i=2 %to 8;,x&i*y&i as z&i %end;
from &aa,&bb;
quit;
%mend;

%macro logistic(data=,dv=,iv=,num=,dnum=,test=);
/* data means what you want do satatistical test on*/
/* dv and iv means dependent variable and independent variables*/
/* dnum is used to specify how many dependant variables includes, like
/*x1 x2 x3...x8, where there are 8 variable and setting dnum=8*/
/* test is dataset, based on which you get predicted yi.*/

data _null_;
iv2 = tranwrd(compbl("&iv"), " ", "+");
dv2 = tranwrd(compbl("&dv"), " ", "+");
call symput('iv2', iv2); /* independant variables array, like weight len...'*/
call symput('dv2', dv2);
run;

%do i=1 %to &dnum;
%let dvv&i=%scan(&dv2,&i,+);
%end;

%do i=1 %to #
%let ivv=%scan(&iv2,&i,+);
proc logistic data=&data outest=estimates;
/* estimated coefficienct stored on dataset estimates;*/
model &ivv=&dvv1-&&dvv&dnum /selection=forward;
run;

data estimates(keep=&dvv1-&dvv2,intercept);
set estimates;
run;
/* keep coefficient for dv and intercept in dataset estimates;*/

%product(aa=estimates,bb=test);
proc sql;
create table y&i as
select z1+z2+z3+z4+z5+z6+z7+z8 as y;
/* where there should be on simplied expression instead of z1+...z8*/
from c;
quit;
%end;
%mend;

shiyiming

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