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.
Matrigitikanjalih “Mātrigītikāñjalih” is a well-known Gitikavya in modern Sanskrit literature. Authored by Harekrishna Meher, this kavya comprises twenty-five Sanskrit songs of different topics and tastes experienced in human life. These songs are written in very lucid, simple, sweet and graceful words that are capable of touching the core of the hearts of readers. The titles of the songs indicate their themes. The style of composition bears a unique and special feature. There is no verbosity or stiffness in language. Words are imbued with proper feelings and sentiments. Alliteration, grace of diction, Upama, Rupaka and other figures of speech are contextually found in this kavya. The poet has presented these songs with his original innovated new metres and tuning. The songs are marked by original thinking and novel ideas.