Algorithm 1SpectralEnvelope (s, k)

Input: DNA sequence s and frequency k Output: Mapping $\mathcal{M}$  1:Compute the set of binary indicator vectors of s  2:Compute ${\mathbf{X}}_k$ using (10) and (12)  3:Eigendecomposition of ${\mathbf{X}}_k^{*}{\mathbf{X}}_k\leftarrow \mathbf{Q}\mathbf{\Lambda }{\mathbf{Q}}^{-1}$  4:${\lambda }_k\leftarrow max\left(\mathrm{diag}(\mathbf{\Lambda })\right)$  5:$\mathbf{w}\leftarrow$ eigenvector of ${\lambda }_k$  6:return$\mathbf{w}$