Mahendra Sà «ri (c. 1340 â 1400) is the 14th century Jain astronomer who wrote the Yantraraja, the first Indian treatise on the astrolabe. He was trained by Madana Sà «ri, and was teacher to Malayendu Sà «ri. Jainism had a strong influence on mathematics particularly in the last couple of centuries BC. By the time of Mahendra Suri, however, Jainism had lost support as a national religion and was much less vigorous.
Mahendra Suri's fame rests on the work YantrarÃÂja, which introduced the astrolabe to the Indian astronomer. Mahendra Sà «ri was patronized by the Tughluq ruler of Delhi, Firà «z ShÃÂh (r. 1351âÂÂ1388), who evinced keen interest in astronomy. Firà «z ShÃÂh had earlier caused the Bá¹Âhatsaá¹Âhitàof VarÃÂhamihira to be translated into Persian. At the sultan's instance, Mahendra Sà «ri studied the astrolabe and introduced it to the Sanskrit audience in 1370 in his YantrarÃÂja. Its circulation was largely, if not wholly, confined to astronomers who worked within the Islamic and Ptolemaic traditions.
The YantrarÃÂja is best described as an astrolabe user's manual. It explains how this king (rÃÂja) of instruments (yantra) is to be constructed and commissioned for purposes of observation. The saumya yantra (northern instrument) projected from the South Pole and the yÃÂmya yantra (southern instrument) projected from the North Pole are discussed separately, followed by a description of the phaá¹Âëndra yantra (the serpentine instrument), which combines both.
A detailed discussion on the application of the astrolabe is found in Malayendu Sà «ri's commentary on the YantrarÃÂja. This commentary is also interesting because it provided, for the first time to Indian astronomers, tables for ready reference, which helped simplify calculations. The commentator gave latitudes of 75 cities. Malayendu made a list of latitudes for 32 stars, which were identified as relevant for purposes of calculations in India.