(c.1530) of Jyesthadeva (c.1500-1610), in the Malayalam language,
is a seminal text or the Kerala School of Astronomy. It presents
detailed explanations and demonstrations for the results and
processes in Mathematical Astronomy. The first half of the
work (chapters I-VII) deals with Mathematics and the topics
covered are: Parikarma (Logistics), Dasaprasna (ten problems),
Bhinnaganita (fractions), Trairasika (rule of three), Kuttakara
(linear indeterminate equations), Paridhi and Vyasa (infinite
series and approximations for the ratio of the circumference
and diameter of a circle) and Jyanayana (infinite series and
approximations for sines). The second half of the work (Chapters
VIII-XV) deals with Mathematical Astronomy and the topics
covered are Grahagati (computation of Mean and true; longitudes
of planets), Bhagolai (celestial sphere), Pancadasa-prasna
(fifteen problems relation to right ascension, declination
etc.), Chayaganita (gnomonic determination of place, time
and direction), Grahana (eclipses), Vyatipata (when sun and
moon have the same declination), Drkkarma (reduction to observation)
and Candrasrngonnati (phases of moon).
Ganitayuktibhasa purports to present an exposition of the mathematics necessary for computation of planetary motions as set forth in the great treatise tantrasamgraha (c. 1500) of Nilakanatha Somayaji. The demonstrations given in Ganitayuktibhasa have been reproduced in the form of Sanskrit verses by sankara Variyar in his commentaries Kriyakramakari (c.1535 on Lilavati and Yuktidipika on Tantrasamgraha. There is also a Sanskrit work entitled Ganitayuktibhasa which seems to be a later and somewhat rough Sanskrit translation of the Malayalam original.
Even thought the importance of Ganitayuktibhasa was brought to the notice of modern scholarship by C.M. Whish in 1835, an edition of the Mathematic part of the text (along with notes in Malayalam) was published only in 1948 by Ramavarma Thampuran and Akhileswara Aiyar. For the first time, a Critical edition of the entire Malayalam text is being brought out along with English Translation and detailed Explanatory Notes as Volume I, II of the present series. Volume III presents a critical edition of the Sanskrit Ganitayuktibhasa.