To the uninitiated, modern jazz can sound like a secret language, full of unpredictable melodies and unexpected rhythms. For alto saxophonist Rudresh Mahanthappa, however, the idea of jazz as code is more than just a metaphor.

Mahanthappa is best known for combining avant-garde jazz with Indian classical music. But for his latest release, Codebook, from Pi Recordings, the artist looked instead to cryptography and number theory for inspiration. (The album's title pays homage to The Code Book, a history of cryptography by the British science writer Simon Singh.)