i was asked to provide references. here's one from ck raju whom i have met and had some discussions with. the force of circumstantial evidence for the invention of the infinetismal calculus in kerala is quite overwhelming. the gregory series should rightly be renamed after madhava, neelakantha, et al based on the usual principle of first discoverer getting the credit.
this is one of the problems i have about the deification of the DWMs. some of the deification rightfully belongs to DIMs (dead indian males). :-)
i also discussed this issue with the manuscriptologist kv sharma. he has the authoritative critical edition of the 'aryabhatiya' to his credit, among many, many other manuscripts in mathematics that show an astonishingly high level of mathematical knowledge that is not acknowledged by europeans to this day.
ian pearce's website has a lot of info on indian mathematics and is worth a visit. the particular page about this topic is. pearce is a young research scholar, and when i talked to him, he said he was convinced that indian mathematics has not gotten anywhere near the recognition it deserves.