下面计算马氏距离的程序
data score;
input num x1-x5@;
label x1='政治' x2='语文' x3='外语' x4='数学' x5='物理';
cards;
1 99 94 93 100 100
2 99 88 96 99 97
3 100 98 81 96 100
4 93 88 88 99 96
5 100 91 72 96 78
6 90 78 82 75 97
7 75 73 88 97 89
8 93 84 83 68 88
9 87 73 60 76 84
10 95 82 90 62 39
11 76 72 43 67 78
12 85 75 50 34 37
;
proc iml;
n=12;p=5;
xx={x4 x5};
use score;
read all var xx into x;
e={[12] 1};
x0=(e*x)/n;
mm=i(12)-j(12,12,1)/n;
a=x`*mm*x;
s=a/(n-1);
si=inv(s);print x0 s si; /*si为s的逆矩阵*/
use score(obs=1);
read all var xx into xx1;
d1=(xx1-x0)*si*(xx1-x0)`; /*d 为马氏距离*/
use score(firstobs=2 obs=2);
read all var xx into xx2;
d2=(xx2-x0)*si*(xx2-x0)`;
use score(firstobs=3 obs=3);
read all var xx into xx3;
d3=(xx3-x0)*si*(xx3-x0)`;
use score(firstobs=4 obs=4);
read all var xx into xx4;
d4=(xx4-x0)*si*(xx4-x0)`;
use score(firstobs=5 obs=5);
read all var xx into xx5;
d5=(xx5-x0)*si*(xx5-x0)`;
use score(firstobs=6 obs=6);
read all var xx into xx6;
d6=(xx6-x0)*si*(xx6-x0)`;
use score(firstobs=7 obs=7);
read all var xx into xx7;
d7=(xx7-x0)*si*(xx7-x0)`;
use score(firstobs=8 obs=8);
read all var xx into xx8;
d8=(xx8-x0)*si*(xx8-x0)`;
use score(firstobs=9 obs=9);
read all var xx into xx9;
d9=(xx9-x0)*si*(xx9-x0)`;
use score(firstobs=10 obs=10);
read all var xx into xx10;
d10=(xx10-x0)*si*(xx10-x0)`;
use score(firstobs=11 obs=11);
read all var xx into xx11;
d11=(xx11-x0)*si*(xx11-x0)`;
use score(firstobs=12 obs=12);
read all var xx into xx12;
d12=(xx12-x0)*si*(xx12-x0)`;print d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 d11 d12;
run;quit;
我不会直接从矩阵x中读取每行数据，只能用 use score(obs=1);read all var xx into xx1;d1=(xx1-x0)*si*(xx1-x0)`; 来计算在第一个观测（即x矩阵的第一行）下的马氏距离，共12个同样的步骤，很繁琐！请哪位高手给个循环模式，可直接一起计算这十二个马氏距离！谢谢！！