% --- start of displayed preamble in the book ---
input metaobj
% --- end of displayed preamble in the book ---
defaultfont:="ptmr8r";
warningcheck:=0;
beginfig(1)
newBox.m2(btex B etex) "dx(1cm)";
newBox.m3(btex C etex) "dy(1cm)";
newMatrix.mata(2,1)(m2,m3);
mata.c=origin;
drawObj(mata);
endfig;
end;