Lalla (720 - 790) was an Inian mathematician, astronomer, and astrologer who belonged to a family of astronomers. His most famous work was entitled Shishyadhividdhidatantra, or "Treatise Which Expands the Intellect of Students." He did not believe in the rotation of the Earth. He is also known for having published the earliest known description of a perpetuum mobile in Shishyadhividdhidatantra.