The lunar theories of al-Baghdādī

Conclusions

We have seen that the first two of al-Baghdādī's three methods originate from his predecessors $\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{H}$ abash and Ya $\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{H}$ yā. On the other hand, the ideas underlying the third method, which may well be due to al-Baghdādī himself, may have inspired al-Kāshī to construct similar two-argument tables in his zīj. This hypothesis is supported by the fact that the zījes of al-Kāshī and of al-Baghdādī exhibit another similarity: they contain the same rule for performing parabolic interpolation in planetary velocities.

One important contribution due to Muslim scientists to the development of the exact sciences in the Middle Ages consists in inventions of improved and more expedient computational methods. Al-Baghdādī's lunar theories therefore represent a stage on this road beginning with Ya $\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{H}$ yā/$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{H}$ abash and terminating with al-Kāshī's highly sophisticated methods.