Chitrabhanu (mathematician)

Chitrabhanu (IAST: Citrabhānu; fl. 16th century) was a mathematician of the Kerala school and a student of Nilakantha Somayaji. He was a Nambudiri brahmin from the town of Covvaram near present day Trissur.[1] He is noted for a karaṇa, a concise astronomical manual, dated to 1530, an algebraic treatise, and a commentary on a poetic text. Nilakantha and he were both teachers of Shankara Variyar.[2][3]

Contributions

He gave integer solutions to 21 types of systems of two simultaneous Diophantine equations in two unknowns.[2] These types are all the possible pairs of equations of the following seven forms:[4]

${\displaystyle \ x+y=a,x-y=b,xy=c,x^{2}+y^{2}=d,x^{2}-y^{2}=e,x^{3}+y^{3}=f,x^{3}-y^{3}=g}$

For each case, Chitrabhanu gave an explanation and justification of his rule as well as an example. Some of his explanations are algebraic, while others are geometric.

References

1. https://books.google.com.au/books?id=rNKGAwAAQBAJ&pg=PA21&redir_esc=y&hl=en#v=onepage&q&f=false
2. Joseph, George Gheverghese (2009), A Passage to Infinity: Medieval Indian Mathematics from Kerala and Its Impact, SAGE Publications India, p. 21, ISBN 9788132104810.
3. Plofker, Kim (2009). Mathematics in India. Princeton: Princeton University Press. pp. 220, 319, 323. ISBN 9780691120676.
4. Hayashi, Takao; Kusuba, Takanori (1998), "Twenty-one algebraic normal forms of Citrabhānu", Historia Mathematica, 25 (1): 1–21, doi:10.1006/hmat.1997.2171, MR 1613702.