WCfft1b WCfft1b2 WCfft1f WCfft1f2 WCost1b WCost1f WRfft1b WRfft1f WSint1b WSint1f

WCfft1f() Function WCfft1f ( N As  Long, C As  Variant  ) One-dimensional complex Fourier transform (complex number representation in Excel format) Purpose WCfft1f computes the one-dimensional Fourier transform of a periodic sequence within a complex array. This is referred to as the forward transform or Fourier analysis, transforming the sequence from physical to spectral space. C(k) = (1/N)ΣC(j)exp(-2πijk/N) (Σ for j = 0 to N-1) (k = 0 to N-1) (i is imaginary unit) This transform is normalized since a call to WCfft1f followed by a call to WCfft1b (or vice-versa) reproduces the original array subject to algorithmic constraints, roundoff error, etc. To represent complex numbers in Excel cells, complex number format in Excel (e.g. 2.5+1i) is used. Worksheet function Complex can be used to input complex numbers into cells. Returns N x 1 Column 1 Rows 1 to N Fourier transformed data sequence Parameters [in] N The length of the sequence to be transformed. (N >= 1) The transform is most efficient when N is a product of small primes. [in] C (N) The complex sequence to be transformed. Reference FFTPACK Example Compute the Fourier transform of the data sequence by WCfft1f. Then compute its backward transform by WCfft1b and confirm that the original data sequence is restored.