Abstract: A method and apparatus to transform time to frequency or frequency to time of data signals is disclosed. A single processing element can be used recursively or can be use modularly to construct the apparatus. The processing element has two input digital data signals and generates to output digital data signals. The processing element also receives a coefficient signal and a plurality of status signals. The processing element computes its output signals in accordance with______________________________________ F=1, S=0 C = A+B D = K*(A-B) F=1, S=1 C = B D = K*(2*A-B) F=0, S=0 C = A+K*B D =A-K*B F=0, S=1 C = 2*K*B D = A-K*B ______________________________________The apparatus also has a storage means to store the coefficients and to store the output of the processing element. A sequencer which is connected to the output storage supplies the same as input to the processing element and controls the processing of the processing element to effectuate the FDCT operation or the IDCT operation.