  The paper by Popova et al. presents an oversimplified mathematical model of
solar activity with a claim of predicting/postdicting it for several millennia
ahead/backwards. The work contains several flaws devaluating the results: (1)
the method is unreliable from the point of view of signal processing (it is
impossible to make harmonic predictions for thousands of years based on only 35
years of data) and lacks quality control, (2) the result of post-diction
apparently contradicts the observational data. (3) theoretical speculations
make little sense, To summarize, a multi-harmonic mathematical model, hardly
related to full solar dynamo theory, is presented, which is not applicable to
realistic solar conditions because of the significant chaotic/stochastic
intrinsic component and strong non-stationarity of solar activity. The obtained
result is apparently inconsistent with the data in the past and thus cannot be
trusted for the future predictions.
