Jyeṣṭhadeva

Jyeṣṭhadeva was an astronomer-mathematician of the Kerala school of astronomy and mathematics founded by Madhava of Sangamagrama. He is best known as the author of the Yuktibhāṣā, a commentary in Malayalam of the treatise Tantrasamgraha by Nilakantha Somayaji. In the Yuktibhāṣā, Jyeṣṭhadeva gave complete proofs and rationales for the statements in Tantrasamgraha, which was unusual for traditional Indian mathematicians of the time. The Yuktibhāṣā is now believed to contain derivations of Taylor and infinite series expansions for certain trigonometric functions. However, it did not combine several ideas under the unifying concepts of the derivative and the integral, show the connection between the two, or turn calculus into the powerful problem-solving tool we have today. Jyeṣṭhadeva also authored Drk-karana, a treatise on astronomical observations.