function b = matVecQt(A,b)
[m,n]=size(A);

for j=1:n
  for i=j+1:m
    b([j,i]) = [sqrt(1-A(i,j)^2),-A(i,j);A(i,j),sqrt(1-A(i,j)^2)]*b([j,i]);
  end
end
