Algorithm 2 ((Minorization–maximization (MM) algorithm to solve P6)

Require: Initialize starting point ${\mathbf{s}}_0$, set ${ϵ}_2>0$.   1. Set $k=0$, compute $f_0=f({\mathbf{s}}_0/u)$.   repeat         2. Set $k=k+1$,         3. Compute ${\mathbf{s}}_k$ via (19), if $\tilde{g}({\mathbf{s}}_k/{\mathbf{s}}_{k-1})>{\tilde{P}}_I$, then compute ${\mathbf{s}}_k$ via Algorithm 1.         4. Compute $f_k=\tilde{f}({\mathbf{s}}_k/(u,{\mathbf{s}}_{k-1}))$.         5. Set ${\mathbf{s}}_k$ as new starting point.   until$|f_k-f_{k-1}|/|f_{k-1}|\le {ϵ}_2$.   6. Output $\mathbf{s}$ as the local optimal solution of P6.