CPU.

An Illustrative Example
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We provide a simple example in this subsection to illustrate the iterative process of RAM. In particular, we consider a sparse frequency spectrum consisting of $K=5$ spikes located at 0.1, 0.108, 0.125, 0.2 and 0.5. We randomly generate the complex amplitudes and randomly select $M=30$ samples among $N=64$ consecutive time-space measurements, with $L=1$. Then, we run the RAM algorithm to reconstruct the frequency spectrum from the samples. Note that the first three frequencies are mutually separated by only about $\frac{0.51}{N}$ and $\frac{1.09}{N}$. Implemented with SDPT3 the RAM algorithm converges in four iterations. We plot the simulation results in Fig. \[Fig:illusexample\], where the first subfigure presents variation of the eigenvalues of $T\sbra{\m{u}^*}$ during the iterations, the second row presents the recovered spectra of the first three iterations, and the last row plots the weighting functions used in the first three iterations. Note that the first iteration, which exploits a constant weighting function and coincides with ANM, can detect a rough area where the first three spikes are located but cannot accurately determine their locations and number. In the second iteration, a weighting function is implemented based on the previous estimate to provide preference of the frequencies 