Kātyāyana (कात्यायन) also spelled as Katyayana (c. 3rd century BCE)[1][2][3] was a Sanskrit grammarian, mathematician and Vedic priest who lived in ancient India.
The Kathāsaritsāgara mentions Kātyāyana as another name of Vararuci, a re-incarnation of Lord Shiva's gana or follower Pushpadanta.
[6] According to the Vamana Purana once the gods had gathered together to discuss the atrocities of the demon Mahishasura and their anger manifested itself in the form of energy rays.
Though the object a word is referring to is non-eternal, the substance of its meaning, like a lump of gold used to make different ornaments, remains undistorted, and is therefore permanent.
Here his text on the sulvasutras dealt with geometry, and extended the treatment of the Pythagorean theorem as first presented in 800 BCE by Baudhayana.