WCfft1b WCfft1b2 WCfft1f WCfft1f2 WCost1b WCost1f WRfft1b WRfft1f WSint1b WSint1f

WCfft1b() Function WCfft1b ( N As  Long, C As  Variant  ) One-dimensional complex Fourier backward transform (complex number representation in Excel format) Purpose WCfft1b computes the one-dimensional Fourier transform of a periodic sequence within a real array. This is referred to as the backward transform or Fourier synthesis, transforming the sequence from spectral to physical space. C(j) = sum(C(k)*exp(2pi*i*j*k/N)) (sum for k=0 to N-1) (j=0 to N-1) (i is imaginary unit) This transform is normalized since a call to WCfft1b followed by a call to WCfft1f (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 backward 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 See example of WCfft1f.