преобразование Фурье
noun any of various functions (as F(u)) that under suitable conditions can be obtained from given functions (as f(x)) by multiplying by eiux and integrating over all values of x and that in scientific instrumentation describe the dependence of the average of a series of measurements (as of a spectrum) on a quantity of interest (as brightness) especially of a very small magnitude — called also Fourier transformation
A technique for expressing a waveform as a weighted sum of sines and cosines. Computers generally rely on the version known as discrete Fourier transform. Named after J. B. Joseph Fourier (1768 -- 1830). See also wavelet, discrete cosine transform.