Which South Indian poet and composer has a school of music where Sooryakantam  is called Chāyāvati ?
Muthuswami Dikshitar Muthuswami Dikshitar (March 24, 1775 – October 21, 1835) was a South Indian poet and composer and is one of the Musical Trinity of Carnatic music. His compositions, of which around 500 are commonly known, are noted for their contemplative nature and for capturing the essence of the raga forms through the vainika (veena) style that emphasises gamakas. They are typically in a slower speed (chowka kala). He is also known by his signature name of Guruguha which is also his mudra (can be found in every one of his songs). His compositions are widely sung and played in classical concerts of Carnatic music.
M. L. Vasanthakumari Madras Lalitangi Vasanthakumari (Tamil: மெட்ராஸ் லலிதாங்கி வசந்தகுமாரி ) (popularly referred to as MLV) (3 July 1928 – 31 October 1990) was a Carnatic musician and playback singer for film songs in many Indian languages. MLV and her contemporaries D. K. Pattammal and M. S. Subbulakshmi were popularly referred to as the "female trinity of Carnatic Music. A prime disciple of the G. N. Balasubramaniam, she was the youngest among the established musicians of that era, and was the youngest female awardee of the "Sangita Kalanidhi" award.