you shall provide more codes

to make your question more clear

proc iml;
   n=10;m=10; p=4;
   use d322(obs=10);
   xx={x1 x2 x3 x4};
   read all  var xx into x; print x;
   ln={[10] 1} ;
   x0=(ln*x)/n; print x0;
   mx=i(n)-j(n,n,1)/n;
   a1=x`*mx*x; print a1;

{[10] 1}   <----> {1 1 1 1 1 1 1 1 1 1} in SAS/IML

[10] 1 is a short-writing format.