Chebyshev spectral differentiation matrix of order n. k determines
the character of the output matrix. For either form, the eigenvector matrix is ill-conditioned.
chebspec(n, k = NULL)Chebyshev spectral differentiation matrix
order of the matrix.
k=0 is the default, no boundary conditions. The matrix is similar to a Jordan block
of size n with eigenvalue 0. If k=1, the matrix is nonsingular
and well-conditioned, and its eigenvalues have negative real parts.