Although there is some evidence of mathematical work in Kerala prior to Madhava ("e.g.", "Sadratnamala" c. 1300, a set of fragmentary results), it is clear from citations that Madhava provided the creative impulse for the development of a rich mathematical tradition in medieval Kerala. However, except for a couple, most of Madhava's original works have been lost. He is referred to in the work of subsequent Kerala mathematicians, particularly in Nilakantha Somayaji's "Tantrasangraha" (c. 1500), as the source for several infinite series expansions, including sin "θ" and arctan "θ". The 16th-century text "Mahajyānayana prakāra" (Method of Computing Great Sines) cites Madhava as the source for several series derivations for π. In Jyeṣṭhadeva's "Yuktibhāṣā" (c. 1530), written in Malayalam, these series are presented with proofs in terms of the Taylor series expansions for polynomials like 1/(1+"x"2), with "x" = tan "θ", etc.