Śaṅkaranārāyaṇa


Sankaranarayana was an Indian astronomer-mathematician in the court of Sthanu Ravi Kulasekhara of the early medieval Chera kingdom in Kerala. He is celebrated as the author of Laghubhaskariyavivarana or Laghubhaskariyavyakha, a detailed commentary on astronomical treatise Laghubhaskariya by 7th century mathematician Bhaskara I.
Sankaranarayana is known to have established an astronomical observatory at the port of Mahodayapuram, present-day Kodungallur, in central Kerala. Laghubhaskariyavivarana explicitly states that it was composed in Saka Year 791. In the second verse of the commentary Sankaranarayana remembers five major predecessors in the field of mathematics, including his possible master Govinda.
The commentary notably mentions an expert astronomer who had travelled to the mleccha country.

Scientific contributions

Astronomical Observatory

According to the commentary, Sankaranarayana installed an astronomical observatory at the Chera capital Mahodayapuram.
  • There are references to an instrument called "Rasichakra" marked by a "Yantravalaya" in the vivarana. This instrument might be the same as the Golayantra/Chakrayantra mentioned by polymath Aryabhata. The Chakrayantra was developed further and called Phalakayantra by Bhaskara I.
  • At the expiry of every ghatika, drums were sounded by the soldiers to announce time.

Mathematical contributions

Laghubhaskariyavivarana covers several the standard mathematical methods of Aryabhata I such as the solution of the indeterminate equation in integers. The standard Indian method involves the use of Euclidean algorithm called kuttakara.

Historiographical significance

Laghubhaskariyavivarana describes "great mansions" in the city of the Mahodayapuram. He marks out the city of Mahodayapuram as a "senamukha". King Ravi Varma had planned to construct an assembly hall in his capital. A number of specific locations in the capital were also mentioned. Gotramallesvara is identifiable with present-day Lokamallesvaram in Kodungallur.

Identification of king Ravi Kulasekhara with Sthanu

Sankaranarayana says that he was patronized by king Ravi, who had the title Kulasekhara. The opening verse of the commentary gives an indirect invocation or praise to the lord called "Sthanu".
Laghubhaskariyavivarana, according to the commentary itself, was composed in the 25th regnal year of king Ravi Kulasekhara.

Date of ''Laghubhaskariyavivarana''

Laghubhaskariyavivarana is dated by the author in three methods.

As a Kali Date (when the ruler made enquiries regarding solar eclipse)

  • "Angartvambara nanda devamanubhir yate dinanam gane"
  • * Anga = 6, Rtu = 6, Ambara = 0, Nanda = 9, Veda = 4, and Manu = 14
  • * Order - 6609414
  • * Reverse Order - 1449066
  • Kali Date - 3967 years and 86 days = 25 Mithuna, Kollam Era 41 = 866 AD

In the Saka Era

  • "Sakabdah punariha candra randhramuni sankhyaya"
  • * Candra = 1, Randhra = 9, and Muni = 7
  • * Order - 197
  • * Reverse Order - 791 = 870 AD

In regnal years

  • Meeting of Guru and Sauri in Capa = 25th regnal year of the king. In the 9th century, these two planets came to Dhanu Rasi simultaneously only in 869 AD.