Vākyakaraṇa is the source book of Vākyapañcāṅga which is a type of almanac popular among Tamil speaking people of South India.[1]InVākyapañcāṅga, the positions of the celestial entities and the timings of celestial events as obtained using the computational methods expounded in the text Vākyakaraṇa. These methods make use of astronomical tables compiled centuries ago. Each entry in such tables is in the form of a vākya, that is, a sentence in Sankrit, and it represents some numerical value encoded using the kaṭapayādi scheme. Different sets of such vākya-s have been compiled for different celestial entities. One such set is Cāndrvākya-s which is a set of 247 values relating to the position of the Moon. The original set of Cāndrvākya-s are attributed to the legendary Kerala astronomer Vararuci. These were later revised by Mādhava of Saṅgamagrāma, another legendary astronmer and mathematician from Kerala. Such collections of vākya-s have been compiled in respect the five planets Mercury, Mars, Venus, Jupiter and Saturn. It may be noted that these vākya-s themselves are not part of the Vākyakaraṇa.
The authorship of the work has not been fully established. However, internal evidences suggest that the author should be somebody hailing from Kanchi in the Tamil country. The date of composition has been determined as c.1282 CE.[2][1] Vākyakaraṇa has been commented upon by Sundararāja, a contemporary of Nīlakaṇṭha Somayājī (1444 – 1545)) the author of Tantrasamgraha.
Even though Vākyakaraṇa is the source book of Vākyapañcāṅga, almanac makers now do not use this work directly. They make use of later modern adaptions of the work like Jyotiṣa Gaṇita Śāstram by Mūnāmpaṇṇai Kṛṣṇa Jyosyar and Parahita Gaṇitaṃ by Swamy Ayyangar of Karayur.[1]
Most of the manuscripts of Vākyakaraṇa are divided into five chapters. However, there is one manuscript that contains an additional sixth chapter and it is believed to a later interpolation. The first chapter is concerned with computations involving the positions of the Sun, the Moon and the Rāhu, the second chapter with the planets, the third chapter with problems involving time, position and direction, the fourth chapter with eclipses and the fifth chapter with the rising and setting of the Mahāpāta-s.
T. S. Kuppanna Sastri and K. V. Sarma have critically assessed the contents of the work thus:[1]
