1. A memristive cross-bar array for determining a dot product, comprising: a number of row lines; a number of column lines intersecting the row lines to form a number of junctions; a number of resistive memory elements coupled between the row lines and the column lines at the junctions, the resistive memory elements to: receive a number of programming signals at the resistive memory devices, the programming signals defining a number of values within a matrix; and receive a number of vector signals at the resistive memory devices, the vector signals defining a number of vector values to be applied to the resistive memory devices; and a current collection line to collect all currents output from the resistive memory devices through their respective column lines, the collected currents equaling a dot product of the matrix values and the vector values.