proc iml;
r=uniform(repeat(0,20,5));

start sd(x);
z=0;
do i=1 to 5;
if x>r[1,i] then
z=z+r[2,i];
else z=z-r[2,i];
end;
print z;
finish sd;

run sd(0.6);

结果提示是 matrix has not been  set to value

不知哪儿出错了，望高人指点。