According to Kannada scholar R. Narasimhacharya, despite the production of some important secular writings, repeated Chola invasions into Kannada lands in the 11th century may have adversely affected literary production. This situation was brought about by intense competition between the Western Chalukyas and their arch-rivals, the Cholas of Tanjore. Among notable writings, Chandraraja's "Madanatilaka" ("Forehead ornament of passion", 1025), written in the "champu" metre, is the earliest available work on erotica in the Kannada language and an adaptation of the Sanskrit "Kamasutra" by Vatsyayana. The narration is a dialogue between the patron and his wife in "posakannada", the most modern Kannada in usage at the time. He was under the patronage of Machiraja, feudatory of King Jayasimha II (also called Jagadekamalla I). Shridharacharya, a Jain Brahmin patronised by King Someshvara I (also called Ahvamalla or Trailokyamalla) showed his ability to write on scientific subjects in "Jatakatilaka" (1049), the earliest available writing on astrology in Kannada, citing the Sanskrit astronomer Aryabhata. His other work is the lost "Chandraprabha Charite", on belles-lettres.