  The elastic behavior of materials operating in the linear regime is
constrained, by definition, to operations that are linear in the imposed
deformation. Though the nonlinear regime holds promise for new functionality,
the design in this regime is challenging. In this paper we demonstrate that a
recent approach based on training [Hexner et al., PNAS 2020, 201922847] allows
responses that are inherently non-linear. By applying designer strains, a
disordered solids evolves through plastic deformations that alter its response.
We show examples of elaborate nonlinear training paths that lead to the
following functions: (1) Frequency conversion (2) Logic gate and (3) Expansion
or contraction along one axis, depending on the sequence of imposed transverse
compressions. We study the convergence rate and find that it depends on the
trained function.
