What it says
Madhava (c. 1340–1425) gave the series in which pi divided by four equals one minus a third plus a fifth minus a seventh, without end, along with ways to correct its tail, and the series for sine and cosine. Nilakantha Somayaji set these out in the Tantrasangraha (1500), and Jyeshthadeva wrote the Yuktibhasha (c. 1530) in Malayalam, giving their proofs. Charles Whish brought them to European notice in a paper of 1834.
What it proves
It shows calculus-like methods worked out in Kerala, in an unbroken guru-shishya line, long before Newton and Leibniz.
