In an apparatus for carrying out a linear transform calculation on a product signal produced by multiplying a predetermined transform window function and an apparatus input signal, an FFT part carries out fast Fourier transform on a processed signal produced by processing the product signal in a first processing part. A conductive gate abuts a gate insulator for controlling conduction of a channel region. The centraliser at each side includes an embracing portion, fixed end, movable end furnished with projections. The first table top portion is provided with a first docking element arranged in an end. The A switching block member 13 is pivotably supported by the carriage. The impedance match element includes a central conductive pin, a supportive element, a ring, and a resistor, wherein the resistor longitudinally extends in a direction that is not coaxial with the longitudinal axis of the central conductive pin.