def METHOD_NAME(dls, shape, pmc):
    """Forward derivative in y."""
    Nx, Ny = shape
    if Ny == 1:
        return sp.csr_matrix((Nx, Nx))
    dyf = sp.csr_matrix(sp.diags([-1, 1], [0, 1], shape=(Ny, Ny)))
    if not pmc:
        dyf[0, 0] = 0.0
    dyf = sp.diags(1 / dls).dot(dyf)
    dyf = sp.kron(sp.eye(Nx), dyf)
    return dyf