Slices of the input, target, output, and error of the frame of reference emulator at the final time step (i.e. with style parameter a = 1). The input is the (scalar) linear density field (first column). The emulator aims to predict the three components (one per row) of its target p − p_LPT (second column). The emulator’s predictions are shown in the third column, and the emulation error p_res = p − p_LPT − p_ML, is shown in the final column.