“Memoirs of the various modes according to which the nations of the southern parts of India divide time” published in 1825, carries an explanation of the trigonometric calculations found in the Surya Siddantha.
The author of one of the memoirs ( page 325) combats the then-prevalent assertion among Europeans that Indians had been following certain methods without understanding them, by using the same methods to compute the lunar eclipse of November 1789. Though not wanting to stir a scientific controversy, he still concedes that it was possible that the Indians knew the principles and the theorems long before the Greeks.
