A skilled musician and coder, the French American pianist Dan Tepfer builds computer programmes that interact with his improvised compositions in manners both musical and visual. In this performance of ‘TriadSculpture’ from his multimedia project Natural Machines (2018), which explores ‘the intersection, in music, between natural and mechanical processes’, Tepfer improvises on piano as visual representations of the chords he plays with his left hand are generated on screen. The result is both a stunning audiovisual experience and a small, curious glimpse into the often hidden patterns and ratios that make music possible.