 The use of infinitesimals to study rates of change can be found in Indian mathematics, perhaps as early as 500 AD, when the astronomer and mathematician Aryabhata (476–550) used infinitesimals to study the orbit of the Moon.The use of infinitesimals to compute rates of change was developed significantly by Bhāskara II (1114–1185); indeed, it has been argued that many of the key notions of differential calculus can be found in his work, such as "Rolle's theorem".The Islamic mathematician, Sharaf al-Dīn al-Tūsī (1135–1213), in his "Treatise on Equations", established conditions for some cubic equations to have solutions, by finding the maxima of appropriate cubic polynomials.