Abstract: A distance measuring circuit includes an array of non-volatile analog storage cells arranged in rows and columns, input circuits to apply complementary analog voltages to pairs of row lines, and current measurement circuits connected to the column lines. Pairs of storage cells in a column are programmed to threshold voltages linearly related to a component of a stored vector and the negative of the component of the stored vector. During distance measurement, input voltages on a corresponding pair of the row lines are similarly linear related to a corresponding component of an input vector and the additive inverse of the component of the input vector. The storage cells are biased in the saturation regions so that the current through each storage cell is approximately proportional to the square of the difference between the voltage on the row line and the cell's threshold voltage, and currents on the column lines indicate the squared distance between user stored analog vectors and the input analog vector.