Lalla (c. 720–790 CE) was an Indian mathematician, astronomer, and astrologer who belonged to a family of astronomers. His most famous work was titled Śiṣya-dhī-vṛddhida-tantra, or "Treatise which expands the intellect of students." He is also known for having published the earliest known description of a perpetuum mobile in Śiṣyadhīvṛddhidatantra.
In his work, Lalla drew on his predecessors Āryabhaṭa, Brahmagupta, and Bhāskara I. In turn, he influenced later generations of astronomers, including Śrīpati, Vaṭeśvara, and Bhāskara II (who wrote a commentary on the Śiṣyadhīvṛddhidatantra).
He followed the Ārya-pakṣa or the school of Āryabhaṭa (continued by Bhāskara I), but divided the mahāyuga the traditional way, following the Brāhma-pakṣa school of Brahmagupta. Although he followed Āryabhaṭa, he did not believe in the rotation of the Earth.
His father's name was Trivikrama, and he lived in central India, possibly in the Lāṭa region in mod