The form of the INTNX function is

INTNX ( interval, from, n < , alignment > ) ;
The arguments to the INTNX function are as follows:

interval
is a character constant or variable that contains an interval name

from
is a SAS date value (for date intervals) or datetime value (for datetime intervals)

n
is the number of intervals to increment from the interval that contains the from value

alignment
controls the alignment of SAS dates, within the interval, used to identify output observations. Allowed values are BEGINNING, MIDDLE, END, and SAMEDAY.

The number of intervals to increment, n, can be positive, negative, or zero.

For example, the statement NEXTMON=INTNX(’MONTH’,DATE,1) assigns to the variable NEXTMON the date of the first day of the month following the month that contains the value of DATE. Thus INTNX(’MONTH’,’21OCT2007’D,1) returns the date 1 November 2007.

data m;
input month y2000 y2001 y2002 y2003;
CARds;
1 19 19 19 19
2 90 90 90 90
3 10 10 10 10
4 25 25 25 25
5 19 19 19 19
6 90 90 90 90
7 10 10 10 10
8 25 25 25 25
9 19 19 19 19
10 90 90 90 90
11 10 10 10 10
12 25 25 25 25
;
proc transpose data=m out=m name=year prefix=data;
by month;
var y2000-y2003;
run;
proc sort data=m;
by year;
run;
data m;
set m(keep=data1);
time=intnx('month','01jan2000'd,_n_-1);
format time yymon7.;
run;
proc gplot data=m;
plot data1*time;
symbol i=join;
run;

/*接上（1）绘制该序列时序图ji样本自相关图
（2）判断该序列的平稳性
（3）判断该序列的纯随机性*/
proc arima data=m;
identify var=data1 stationarity= (adf=1);/*3个要求都在里面了*/
run;