Tamil Heritage Trust
May 3, 2025 - Online talk in English titled "Uyirēḻuttu System of Numeration Used in Tamil Astronomy Texts"
A majority of source texts of Indian mathematics and astronomy are
written in the verse format. Hence, they and even their prose
commentaries, make use of a variety of numeration systems in which
linguistic phrases—syllables, words, or set of sounds—are employed to
represent arbitrary numerical values. The bhūta-saṅkhyā, Āryabhaṭīya,
and kaṭapayādi systems of numeration are well known and have been
discussed in many scholarly and popular books and articles.
In their Talk for THT, Dr V Ramanathan of IIT-BHU, Dr Venketeswara Pai
of IISER Pune and Prof M D Srinivas of CPS, Chennai examine a less-known
but significant system developed within the Tamil Astronomy tradition,
discussing the 12th - 13th century astronomical work Cūḍāmaṇi
Uḷḷamuḍaiyān by Tirukkoṭṭiyūr Nambi, which uses a vowel-based numeration
scheme (uyirēḻuttu) to encode arbitrary numbers by a method that is
significantly distinct from systems mentioned above. In particular, its
use in encoding lunar longitudes and its application in the formulation
of the 248 Candravākyas (sometimes referred to as the Pańcāṅgavākyas)
in Tamil.
YouTube link to the talk
Dr. V. Ramanathan is a physical chemist in the Department of
Chemistry at IIT(BHU) Varanasi and heading the IKS Center of the
institute. He carried out his post-doctoral research works in University
of Stuttgart in Germany, University of Basel in Switzerland and Seoul
National University in South Korea. He obtained his PhD from IIT Kanpur,
India. His areas of current academic research are Raman imaging and
spectroscopy, SERS and computational chemistry. His other research
interest lies in studying the scientific heritage of India. He is a
Fulbright scholar and a former core committee member of Indian National
Young Academy of Science (a body of Indian National Science Academy
(INSA).
Dr. Venketeswara Pai is a renowned scholar in the field of
Indian mathematics and astronomy, with expertise in Sanskrit scientific
literature, manuscript studies, and traditional knowledge systems. As a
faculty member at IISER Pune, he has made significant contributions to
the study of historical mathematical texts, their interpretations, and
their relevance within the broader framework of Indian Knowledge Systems
(IKS). He has done extensive research on Indian astronomical treatise
making use of his strong background in philology and mathematical
analysis and computation. Dr. Pai has authored numerous articles in
peer-reviewed journals and books, receiving prestigious awards for his
research in Indian astronomy and mathematics.
Prof. M. D Srinivas is Chairman of Centre for Policy Studies at
Chennai, a Research institute which he founded along with Dr. J. K.
Bajaj and a few colleagues with the objective of comprehending India
from an Indian perspective. After completing his PhD in University of
Rochester, New York, USA, Srinivas taught at the Department of
Theoretical Physics, University of Madras during 1976-1996. His areas of
interest are: Conceptual and mathematical foundations of quantum
mechanics; Indian scientific tradition, especially Indian mathematics
and astronomy; and Society, polity and economy of India in the
Eighteenth century. He has published significant works in all these
fields. He was selected a Fellow of Indian National Science Academy in
2023 for his work on History and Philosophy of Science. His name has
been included among the list of Padma Shri awardees this year.

Tamil Heritage Trust
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