Kelallur Nilakantha Somayaji was a major mathematician and astronomer of the
Kerala school of astronomy and mathematics. One of his most influential
works was the comprehensive astronomical treatise Tantrasamgraha completed in
1501. He had also composed an elaborate commentary on Aryabhatiya called the
Aryabhatiya Bhasya. In this Bhasya, Nilakantha had discussed infinite series
expansions of trigonometric functions and problems of algebra and spherical
geometry. Grahapareeksakrama is a manual on making observations in astronomy
based on instruments of the time. Biographical details
Nilakantha Somayaji was one of the very few authors of the scholarly traditions
of India who had cared to record details about his own life and times. So
fortunately a few accurate particulars about Nilakantha Somayaji are known.
In one of his works titled Siddhanta-star and also in his own
commentary on Siddhanta-darpana, Nilakantha Somayaji has stated that he
was born on Kali-day 1,660,181 which works out to 14 th June 1444 CE. A
contemporary reference to Nilakantha Somayaji in a Malayalam work on
astrology implies that Somayaji lived to a ripe old age even to become a
centenarian. Sankara Variar, a pupil of Nilakantha Somayaji, in his commentary
on Tantrasamgraha titled Tantrasamgraha-vyakhya, points out that
the first and last verses of Tantrasamgraha contain chronograms
specifying the Kali-days of the commencement and of completion of
Somayaji's magnum opus Tantrasamgraha. Both these days occur in 1500 CE.
In Aryabhatiya-bhashya, Nilakantha Somayaji has stated that he was the son
of Jatavedas and he had a brother named Sankara. Somayaji has further stated
that he was a Bhatta belonging to the Gargya-gotra and was a follower of
Asvalayana-sutra of Rigveda. References in his own Laghuramayana indicate that
Nilakantha Somayaji was a member of the Kelallur family residing at Kundagrama,
now known as Trikkandiyur in modern Tirur, Kerala. His wife was named Arya
and he had two sons Rama and Dakshinamurti.
Nilakantha Somayaji studied vedanta and some aspects of astronomy under one
Ravi. However, It was Damodara, son of Kerala-drgganita author Paramesvara, who
initiated him into the science of astronomy and instructed him in the
basic principles of mathematical computations. The great Malayalam poet
Thunchaththu Ramanujan Ezhuthachan is said to have been a student of
Nilakantha Somayaji. The epithet Somayaji is a title assigned
to or assumed by a Namputiri who has performed the vedic ritual of Somayajna.
So it could be surmised that Nilakantha Somayaji had also performed a Somayajna
ritual and assumed the title of a Somayaji in later life. In colloquial
Malayalam usage the word Somayaji has been corrupted to Comatiri.
Nilakantha Somayaji as a polymath Nilakantha's writings substantiate his
knowledge of several branches of Indian philosophy and culture. It is said that
he could refer to a Mimamsa authority to establish his view-point in a debate and
with equal felicity apply a grammatical dictum to the same purpose. In his
writings he refers to a Mimamsa authority, quotes extensively from
Pingala's chandas-sutra, scriptures, Dharmasastras, Bhagavata and
Vishnupurana also. Sundararaja, a contemporary Tamil astronomer, refers to
Nilakantha as sad-darshani-parangata, one who had mastered the six systems of
Indian philosophy. Astronomy
In his Tantrasangraha, Nilakantha revised Aryabhata's model for the
planets Mercury and Venus. His equation of the centre for these planets remained
the most accurate until the time of Johannes Kepler in the 17th century.
In his Aryabhatiyabhasya, a commentary on Aryabhata's Aryabhatiya, Nilakantha
developed a computational system for a partially heliocentric planetary model
in which Mercury, Venus, Mars, Jupiter and Saturn orbit the Sun, which in turn
orbits the Earth, similar to the Tychonic system later proposed by Tycho
Brahe in the late 16th century. Most astronomers of the Kerala school who
followed him accepted this planetary model.
Works of Nilakantha Somayaji The following is a brief description of
the works by Nilakantha Somayaji dealing with astronomy and mathematics.
Tantrasamgraha Golasara : Description of basic
astronomical elements and procedures Sidhhantadarpana : A short work in 32
slokas enunciating the astronomical constants with reference to the Kalpa
and specifying his views on astronomical concepts and topics.
Candrachayaganita : A work in 32 verses on the methods for the calculation of
time from the measurement of the shadow of the gnomon cast by the moon and vice
versa. Aryabhatiya-bhashya : Elaborate
commentary on Aryabhatiya. Sidhhantadarpana-vyakhya : Commentary on
his own Siddhantadarapana. Chandrachhayaganita-vyakhya : Commentary
on his own Chandrachhayaganita. Sundaraja-prasnottara : Nilakantha's
answers to questions posed by Sundaraja, a Tamil Nadu based astronomer.
Grahanadi-grantha : Rationale of the necessity of correcting old astronomical
constants by observations. Grahapariksakrama : Description of the
principles and methods for verifying astronomical computations by regular
observations. Jyotirmimamsa : Analysis of astronomy
See also Indian mathematicians
Tantrasamgraha Official Website Official Website of Kelallur Nilakantha Somayaji
References Further reading
R.C. Gupta. "Second order interpolation in Indian mathematics up to the fifteeth
century". Indian Journal of History of Science 4: 87–98.
Shailesh A Shirali. "Nilakantha, Euler and pi". Resonance: 28–43. Retrieved 1
February 2010. Ranjan Roy. "The discovery of the series
formula for π by Leibnitz, Gregory and Nilakantha". Mathematics Magazine 63:
291–306. doi:10.2307/2690896. Retrieved 18 January 2010.