Person: Al-Khalili

Al-Khalili was an Islamic astronomer who compiled extensive tables for astronomical use.

Of course, giving tables for timekeeping using astronomical events, requires a thorough understanding of geometry on the sphere and the work by al-Khalili can be seen as the end-product of the work of the Arabs on this mathematical topic.
Of course, al-Khalili did not do all this work without basing some of it on the work of earlier mathematicians, to see the magnitude of his task note that one table alone contains over 13000 entries.
Al-Mizzi died around 1350 and the first two of al-Khalili's tables were improved versions of the ones produced by al-Mizzi, where al-Khalili had taken more accurate values for the terrestrial coordinates of Damascus.
Al-Khalili's tables for solving the problems of spherical astronomy can be seen to be tables which solve spherical triangles using a method similar to the modern cosine rule.
computer-based tests to determine, if possible, the methods of computation used by al-Khalili in the construction of his auxiliary tables.
The tables produced by al-Khalili for the direction of Mecca must have been calculated using his own auxiliary tables (which would be the most accurate available).
This is a greater degree of accuracy than would result if al-Khalili used his auxiliary tables in their present form.
One possible solution is that al-Khalili had computed more accurate auxiliary tables before calculating his tables for the direction of Mecca but these are now lost.

Born about 1320, possibly Damascus, Syria. Died about 1380, possibly Damascus, Syria.

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Astronomy, Origin Syria

Thank you to the contributors under CC BY-SA 4.0!

O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive