Stimuli-responsive materials that compute represent a new way of using the diverse capabilities of polymeric systems – exploiting chemical changes to create functional structures that receive, process, and respond to information that enters the system in the form of a stimulus. Herein, we present a polymer with a nonlinear optical response – namely, a light-induced increase in refractive index – and describe how this response can form the basis of computing-inspired functions. The photopolymerizable cuboid performs three computing operations: data recognition and transfer; volumetric encoding, and binary arithmetic. Binary data, input in the form of three broad, mutually orthogonal beams of white light patterned with light (1) and dark (0) stripes, elicits the formation of up to three populations of filaments or waveguides within volume subdivisions (voxels) of the cuboid. Spontaneous self-organization of orthogonal waveguide populations yields ordered configurations that may be read at the sample output to perform operations.