Utilities.bandPopulate(L, kl, 0);
Utilities.addDiagonal(L, 1);
while (!Utilities.spd(L))
Utilities.addDiagonal(L, 1);
U = new UpperSPDBandMatrix(n, ku);
Utilities.bandPopulate(U, 0, ku);
Utilities.addDiagonal(U, 1);
while (!Utilities.spd(U))
Utilities.addDiagonal(U, 1);