The corpus, every claim citable.

The Tantrasaṅgraha of Nīlakaṇṭha Somayājī (Kerala, c. 1500 CE) states the alternating series π/4 = 1 − 1/3 + 1/5 − 1/7 + … as a verse rule for the circumference of a circle of given diameter, together with a rational end-correction that sharply accelerates convergence. The Kerala school's commentaries attribute the series to Mādhava (c. 1340–1425). Leibniz published the same series in Europe in 1673; Charles Whish first reported the Kerala texts to European scholarship in 1834.

On the Hindu Quadrature of the Circle, and the Infinite Series of the Proportion of the Circumference to the Diameter Exhibited in the Four Sastras · 1500