Errata
page 4, system (0.14): Dq,z should be noted
Hq,z to avoid any confusion with the
q-derivation operator. With the latter,
Dq,z-Q should read
(q-1)zDq,z-Q+1.
page 20, right before section 2: read
p2n+1=u2+(n+1)Dx2
instead of
p2n+1=u2+nDx2.
page 28, definition of py in example: read
2x+4y instead of 2x+2y.
page 38, second example: incorrect sign in definition of
R; read
(s2-s+x)DsDx+2Ds
instead of
(s2-s+x)DsDx-2Ds.