Abstract
Renowned Indian astronomer and mathematician Nīlakaṇṭha Somayājī is well known for his innate ability to provide ingenious proofs. In his elaborate commentary on Āryabhaṭīya called Āryabhaṭīyabhāṣya, we find elegant upapattis or rationales for three algebraic identities involved in calculating cubes and cube-roots. In this paper, we detail these upapattis which may be called dissection proofs in the modern parlance. Incidentally, Nīlakaṇṭha’s simple, yet concise and convincing demonstrations are pertinent in the context of mathematics pedagogy as well.
Similar content being viewed by others
Change history
30 December 2021
Due to a font problem some mistakes occurred that have been corrected.
Notes
As the adage goes:
अर्धमात्रालाघवेन पुत्रोत्सवं मन्यन्ते वैयाकरणाः।
In the commentary of the sūtra कृत्यल्युटो बहुलम् (3.3.113) we find the vārtika कृतो बहुलम् पादहारकाद्यर्थम्।
Some of the verses are in Gīti meter which essentially comes under the Āryā class of moric meters.
This is not to undermine the significance of the commentary of Bhāskara I (7th cent.), which is also an extremely important and elaborate commentary. What may be worth noting is the fact that the nature, style and emphasis of the two commentaries widely vary from one another.
The following statement of Nīlakaṇṭha appears in his commentary on verse 26 of the Gaṇita section (Āryabhaṭīya of Āryabhaṭācārya 1930, p. 156):
... मयाद्य प्रवयसा ज्ञाता युक्तीः प्रतिपादयितुं भास्करादिभिः अन्यथा व्याख्यातानां कर्माण्यपि प्रतिपादयितुं यथाकथञ्चिदेव व्याख्यानमारब्धम्।
... somehow, I have started the commentary today at my ripe age, in order to present the rationales that have been understood by me, and also to describe the procedures explained differently by Bhāskara, etc.
This is as per the sūtra of Pāṇini:
प्रैषातिसर्गप्राप्तकालेषु कृत्याश्च (3.3.163).
Here the word ghane is to be understood as ghanākhye gaṇitakarmaṇi (in the mathematical procedure for determining cubes).
वायुकोणे इत्यर्थः।
In the only edition of the text that is currently available, the first two words have been clubbed together and printed as षडेतेनैव। Such a reading could thoroughly confuse the readers as they may be tempted to split the word षट्+एतेन+एव, which would lead to completely different meaning that does not make any sense in the present context.
References
Āryabhaṭīya of Āryabhaṭa. (1976). Cr. Ed. with introduction, English translation, notes, comments and indexes by K. S. Shukla in collaboration with K. V. Sarma. Indian National Science Academy.
Āryabhaṭīya of Āryabhaṭācārya with the commentary of Nīlakaṇṭha Somasutvan. (1930). Ed. by K. Sāmbaśiva Śāstrī. Part 1, Gaṇitapāda. Trivandrum Sanskrit Series 101. Trivandrum.
Boyer, C. B. (1959). The history of the calculus and its conceptual development. Dover Publications.
Colebrooke, H. T. (1837). Miscellaneous essays (Vol. 2). Allen and Co.
Kline, M. (1973). Mathematical thought from ancient to modern times. Proceedings of the Edinburgh Mathematical Society, 18(4), 340–341.
Larbi, E., & Mavis, O. (2016). The use of manipulatives in mathematics education. Journal of Education and Practice, 7(36), 53–61.
Līlāvatī of Bhāskarācārya with Buddhivilāsinī and Vivaraṇa. (1939) Ed. by Dattātreya Viśṇu Āpaṭe. 2 vols. Ānandāśrama Sanskrit Series.
Mahesh, K. (2010). A critical study of Siddhāntadarpaṇa of Nīlakaṇṭha Somayājī. Ph.D. Thesis. IIT Bombay.
Mallaya, V. M. (2001). Interesting visual demonstration of series summation by Nīlakaṇṭha. Gaṇita Bhāratī, 23, 111–119.
Mallayya, V.M. (2002). Geometrical Approach to Arithmetic Progressions from Nīlakaṇṭha’s Āryabhaṭīyabhāṣya and Śaṅkara’s Kriyākramakarī. In Proceedings of the International Seminar and Colloquium on 1500 Years Of Āryabhateeyam (pp. 143–147).
Narasimha, R. (2012). Pramāṇas, proofs, and the Yukti of Classical Indic Science. In A. Bala (Ed.), Asia, Europe, and the emergence of modern science: Knowledge crossing boundaries (pp. 93–109). Palgrave Macmillan US.
Ojose, Bobby. (2011). Mathematics literacy: Are we able to put the mathematics we learn into everyday use. Journal of Mathematics Education, 4(1), 89–100.
Ramasubramanian, K., Srinivas, M. D., & Sriram, M. S. (1994). Modification of the earlier Indian planetary theory by the Kerala astronomers (c. 1500 AD) and the implied heliocentric picture of planetary motion. Current Science, 66(10), 784–790.
Ramasubramanian, K., & Sriram, M. S. (2011). Tantrasaṅgraha of Nīlakaṇṭha Somayājī. Springer.
Ramasubramanian, K. (2011). The notion of proof in Indian science. In S. R. Sarma & G. Wojtilla (Eds.), Scientific literature in Sanskrit (pp. 1–39). Motilal Banarsidass.
Saraswati Amma, T. A. (1999). Geometry in ancient and medieval India. Motilal Banarasidass.
Siddhāntadarpaṇa of Nīlakaṇṭha Somayājī with autocommentary. (1977). Cr. Ed. by K. V. Sarma. Punjab University. Hoshiarpur: Vishveshvaranand Vishva Bandhu Institute of Sanskrit and Indological Studies.
Srinivas, M. D. (2005). Proofs in Indian mathematics. In Emch, G. G., Sridharan, R., & Srinivas, M. D (Eds.), Contributions to the history of Indian mathematics (pp. 209–248). Hindustan Book Agency.
Acknowledgements
One of the authors Dr. K. Mahesh would like to place on record his sincere gratitude to the project on History of Mathematics in India (HoMI), IIT Gandhinagar, which generously funded this study. The other authors would like to acknowledge MHRD for the generous support extended to them to carry out research activities on Indian science and technology by way of initiating the Science and Heritage Initiative (SandHI) at IIT Bombay. The authors are also thankful for the valuable inputs from the referee of this journal.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Mahesh, K., Sooryanarayan, D.G. & Ramasubramanian, K. Elegant dissection proofs for algebraic identities in Nīlakaṇṭha’s Āryabhaṭīyabhāṣya. Indian J Hist. Sci. 56, 71–84 (2021). https://doi.org/10.1007/s43539-021-00017-x
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s43539-021-00017-x