  The problem of photoionization of atomic hydrogen in a white-dwarf-strength
magnetic field is revisited to understand the existing discrepancies in the
positive-energy spectra obtained by a variety of theoretical approaches
reported in the literature. Oscillator strengths for photoionization are
calculated with the adiabatic-basis-expansion method developed by Mota-Furtado
and O'Mahony [Phys. Rev. A {\bf 76}, 053405 (2007)]. A comparative study is
performed between the adiabatic-basis-expansion method and our previously
developed coupled-channel theory [Phys. Rev. A {\bf 94}, 033422 (2016)]. A
detailed analysis of the positive-energy spectra obtained here and those from
other theoretical approaches shows that the adiabatic-basis-expansion method
can produce more accurate positive-energy spectra than other reported
approaches for low field strengths.
