M:=RandomMat(4000,4000);;
N:=RandomMat(4000,4000);;
s:=ChildCreate();;
Exec("date +%M:%S");
Mtop:=M{[1..2000]};;
Mbottom:=M{[2001..4000]};;
ChildPut(Mtop,"Mtop",s);
ChildPut(N,"N",s);
ChildCommand("Atop:=Mtop*N;;",s);;
Abottom:=Mbottom*N;;
A:=ChildGet("Atop",s);;
Append(A,Abottom);;
ChildKill(s);
Exec("date +%M:%S");
Exec("date +%M:%S");B:=M*N;;Exec("date +%M:%S");
