A computer-usable medium having computer-readable program code embodied therein for causing a computer system, an input device, a memory, and a display, to perform a Fast Fourier transformation, comprising the steps of:
- (a) first computing one of a sum of and a difference between two first pieces of integer data;
- (b) second computing one of a sum of and a difference between two second pieces of integer data;
- (c) multiplying each results of steps (a) and (b) by sine and cosine wave data, respectively;
- (d) computing one of a sum of and a difference results of step (c);
- (e) standardizing to a predetermined bit width of the two pieces of integer data as input for steps(a) and (b);
- (f) standardizing a bit width of at least one of results of steps (a), (b), (c), and (d) to the predetermined bit width by truncating part of output data therefore
- (g) determining a size of input data;
- and
- (h) adjusting the predetermined bit width of step (e) in accordance with the of step (g).