Fast Fourier Transform -- from Wolfram MathWorld The fast Fourier transform (FFT) is a discrete Fourier transform algorithm which reduces the number of computations needed for N points from 2N^2 to 2NlgN, where lg is the base-2 logarithm. If the function to be transformed is not harmonically related to
Sinc函数- 维基百科,自由的百科全书 在x = −6π 到6π 区间显示在同样尺度上的归一化sinc(x)(蓝色)与非归一化sinc 函数 (红色) ... 表示,有两个定义,有时区分为归一化sinc函数和非归一化的sinc函数。
Table of Fourier Transform Pairs Function, f(t). Fourier Transform, F(w). Definition of Inverse Fourier Transform. Р. ¥ ... sinc(t) β(ω). Boxcar in frequency. (7) f (t) iω ̂f(ω). Derivative in time. (8) f (t).