data d321;
input num x1-x3;
cards;
1 3.7 48.5 9.3
2 5.7 65.1 8.0
3 3.8 47.2 10.9
4 3.2 53.2 12.0
5 3.1 55.5 9.7
6 4.6 36.1 7.9
7 2.4 24.8 14.0
8 7.2 33.1 7.6
9 6.7 47.4 8.5
10 5.4 54.1 11.3
11 3.9 36.9 12.7
12 4.5 58.8 12.3
13 3.5 27.8 9.8
14 4.5 40.2 8.4
15 1.5 13.5 10.1
16 8.5 56.4 7.1
17 4.5 71.6 8.2
18 6.5 52.8 10.9
19 4.1 44.1 11.2
20 5.5 40.9 9.4
;
proc iml;
use d321;
xa={x1 x2 x3};
read all var xa into x;
b= x[,1];
/* c=j[nn-1,1];*/
nn=nrow(b);
do i=1 to nn-1 by 1;
c=(b[i+1]-b)/b;
print c;
end;
quit;
上面得到很多c,如何得到一个矩阵c,包含所有i得到的计算值呢。谢谢指导。