| Śaṅkaranārāyaṇa | |
|---|---|
| Born | c.840 CE |
| Died | c.940 CE |
| Residence | Kodungallur in Kerala, India |
| Nationality | Indian |
| Ethnicity | Namputiri |
| Occupation | Astronomer-mathematician |
| Known for | Setting up the Mahodayapuram observatory, the first astronomical observatory in India |
| Notable works | Laghu-bhāskarīya-vivaraṇa |
| Influenced by | A disciple of Govindasvami (c. 800 – c. 860) |
| Religion | Hindu |
Śaṅkaranārāyaṇa (c. 840 – c. 900) was an Indian astronomer and mathematician in the court of King Sthanu Ravi Varman (844- 885 CE) of the Kulasekhara dynasty (Second Cheras) in Kerala.[1] He is believed to have established the first astronomical observatory in India at Kodungallur in Kerala.[1][2] His most famous work was the Laghubhāskarīyavivaraṇa[3] which was a commentary on the Laghubhāskarīya of Bhaskara I which in turn is based on the work of Aryabhata I.[4] The Laghubhāskarīyavivaraṇa was written 869 CE for the author writes in the text that it is written in the Shaka year 791 which translates to a date CE by adding 78.[4]
Śaṅkaranārāyaṇa was a student of the astronomer and mathematician Govindasvami (c. 800 – c. 860).
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Information on observatories in India is meager. Many astronomers patronized by kings carried out astronomical observations. The places of these observations could be called as observatories. The first extant reference to a place of observation with some instruments in India is in the treatise Laghubhāskarīyavivaraṇa authored by Śaṅkaranārāyaṇa. In this work, Śaṅkaranārāyaṇa speaks of a place with instruments in the capital city Mahodayapuram of King Sthanu Ravi Varma of the Kulasekhara dynasty in Kerala. Mahodayapuram has been identified with the present day Kodungallur.[1] The observatory was fitted with an armillary sphere which is a model of the celestial sphere. At the directions of Śaṅkaranārāyaṇa, in every 'Kadigai' duration of 34 minutes, bells were sounded at different important centres of the town to announce correct time.
The following is a translation of the verses in Laghubhāskarīyavivaraṇa containing references to the existence of an observatory in Mahodayapura:[5]
Laghubhāskarīyavivaraṇa covers the standard mathematical methods of Aryabhata I such as the solution of the indeterminate equation by = ax ± c (a, b, c integers) in integers which is then applied to astronomical problems. The Indian method involves using the Euclidean algorithm. It is called kuttakara ("pulveriser").[4]
The most unusual feature of the Laghubhāskarīyavivaraṇa is the use of katapayadi system of numeration as well as the place-value Sanskrit numerals which Laghubhāskarīyavivaraṇa frequently uses.[4] Śaṅkaranārāyaṇa is the first author known to use katapayadi system of numeration with this name but he did not invent it for it appears to be identical to a system invented earlier which was called varnasamjna. The numeration system called varnasamjna was invented by the astronomer Haridatta, and it was explained by him in a text which was written in 684.
The system is based on writing numbers using the letters of the Indian alphabet:
Under this system 1 to 5 are represented by four different letters. For example 1 is represented by the letters ka, ta, pa, ya which give the system its name (ka, ta, pa, ya becomes katapaya). Then 6, 7, 8 are represented by three letters and finally nine and zero are represented by two letters. The system was a spoken one in the sense that consonants and vowels which are not vocalised have no numerical value. The system is a place-value system with zero. In fact many different "words" could represent the same number and this was highly useful for works written in verse.
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