Rematrix is a generative MIDI tool built around two independently programmable probability matrices, enabling intricate rhythmic and melodic pattern transformation for up to four input notes. The upper grid determines the likelihood of time-based events, with each horizontal lane representing a potential rhythmic multiplier of the current grid length—empty lanes yield silence, while more active steps increase the chance of triggering. Multipliers can be set to zero to deactivate notes at specific steps. The lower grid applies identical logic to pitch selection, assigning probabilities to specific notes. Additional controls below the grids govern default velocity, global deviation, and note length. A timing divisor allows for tupletted microrhythmic resolution, and pitch output can be shifted in octaves. Enable scale awareness to ensure harmonically relevant melodic output across patterns.