1. A multi-functional fuzzy logic circuit comprising: at least one input circuit, to which at least one input current is fed, for producing at least one output current of the same value in the same direction as the input current and at least one output current of the same value in the reverse direction, and a plurality of fuzzy logic circuits for executing different fuzzy logic operations, each of said fuzzy logic circuits having as its input at least one of said output currents produced by said at least one input circuit.