1. A distance measuring circuit comprising: an array of analog storage cells arranged in rows and columns; row lines, each coupled to control gates of a row of the analog storage cells; column lines, each coupled to current carrying terminals of a column of analog storage cells; an input circuit which simultaneously applies to the row lines, parallel analog voltages which depend on the components of an input vector; and an output block coupled to the column lines, wherein the output block measures magnitudes of currents to the column lines.