A three-dimensional processor (3D-processor) for calculating mathematical functions in parallel, comprises a larger number (e.g. at least one thousand) of computing elements, with each computing element comprising at least one three-dimensional memory (3D-M) array for storing at least a portion of a look-up table (LUT) for a mathematical function and an arithmetic logic circuit (ALC) for performing arithmetic operations on the LUT data. Even though each individual 3D-M cell is slower than a conventional two-dimensional memory (2D-M) cell, this deficiency in speed is offset by a significantly larger scale of parallelism.