Which South Indian poet and composer has a school of music where Sooryakantam  is called Chāyāvati ?
Suryakantam Suryakantam or Sooryakantam (pronounced sūryakāntam) is a rāgam in Carnatic music (musical scale of South Indian classical music). It is the 17th "melakarta" rāgam (parent scale) in the 72 "melakarta" rāgam system of Carnatic music. It is called Chāyāvati in Muthuswami Dikshitar school of Carnatic music.
Melpathur Narayana Bhattathiri Melpathur Narayana Bhattathiri (Malayalam: മേല്പത്തൂർ നാരായണ ഭട്ടതിരി ; 1560–1646/1666), third student of Achyuta Pisharati, was a member of Madhava of Sangamagrama's Kerala school of astronomy and mathematics. He was a mathematical linguist (vyakarana). His most important scholarly work, "Prkriya-sarvawom", sets forth an axiomatic system elaborating on the classical system of Panini. However, he is most famous for his masterpiece, "Narayaneeyam", a devotional composition in praise of Guruvayoorappan (Krishna) that is still sung at Guruvayoor Temple.