**Sripati**'s father was Nagadeva (sometimes written as Namadeva) and Nagadeva's father, Sripati's paternal grandfather, was Kesava. Sripati was a follower of the teaching of Lalla writing on astrology, astronomy and mathematics. His mathematical work was undertaken with applications to astronomy in mind, for example a study of spheres. His work on astronomy was undertaken to provide a basis for his astrology. Sripati was the most prominent Indian mathematicians of the 11

^{th}Century.

Among Sripati's works are: *Dhikotidakarana* written in 1039, a work of twenty verses on solar and lunar eclipses; *Dhruvamanasa* written in 1056, a work of 105 verses on calculating planetary longitudes, eclipses and planetary transits; *Siddhantasekhara* a major work on astronomy in 19 chapters; and *Ganitatilaka* an incomplete arithmetical treatise in 125 verses based on a work by Sridhara.

The titles of Chapters 13, 14, and 15 of the *Siddhantasekhara* are Arithmetic, Algebra and On the Sphere. Chapter 13 consists of 55 verses on arithmetic, mensuration, and shadow reckoning. It is probable that the lost portion of the arithmetic treatise *Ganitatilaka* consisted essentially of verses 19-55 of this chapter. The 37 verses of Chapter 14 on algebra state various rules of algebra without proof. These are given in verbal form without algebraic symbols. In verses 3, 4 and 5 of this chapter Sripati gave the rules of signs for addition, subtraction, multiplication, division, square, square root, cube and cube root of positive and negative quantities. His work on equations in this chapter contains the rule for solving a quadratic equation and, more impressively, he gives the identity:

√(Other mathematics included in Sripati's work includes, in particular, rules for the solution of simultaneous indeterminate equations of the first degree that are similar to those given by Brahmaguptax+ √y) = √[(x+ √(x^{2}-y)]/2 + √[(x- √(x^{2}-y)]/2)

Sripati obtained more fame in astrology than in other areas and it is fair to say that he considered this to be his most important contributions. He wrote the *Jyotisaratnamala* which was an astrology text in twenty chapters based on the *Jyotisaratnakosa* of Lalla. Sripati wrote a commentary on this work in Marathi and it is one of the oldest works to have survived that is written in that language. Marathi is the oldest of the regional languages in Indo-Aryan, dating from about 1000.

Another work on astrology written by Sripati is the *Jatakapaddhati* or *Sripatipaddhati* which is in eight chapters and is [1]:-

Genethlialogy was the science of casting nativities and it was the earliest branch of astrology which claimed to be able to predict the course of a person's life based on the positions of the planets and of the signs of the zodiac at the moment the person was born or conceived.... one of the fundamental textbooks for later Indian genethlialogy, contributing an impressive elaboration to the computation of the strengths of the planets and astrological places. It was enormously popular, as the large number of manuscripts, commentaries, and imitations attests.

There is one other work on astrology the *Daivajnavallabha* which some historians claim was written by Sripati while other claim that it is the work of Varahamihira. As yet nobody has come up with a definite case to show which of these two is the author, or even whether the author is another astrologer.

**Article by:** *J J O'Connor* and *E F Robertson*

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