WCfft1b WCfft1b2 WCfft1f WCfft1f2 WCost1b WCost1f WRfft1b WRfft1f WSint1b WSint1f

WCost1b() Function WCost1b ( N As  Long, R As  Variant  ) One-dimensional cosine backward transform Purpose WCost1b computes the one-dimensional Fourier transform of an even sequence within a real array. This is referred to as the backward transform or Fourier synthesis, transforming the sequence from spectral to physical space. R(j) = sum(R(k)cos(pi*j*k/(N-1))) (sum for k=0 to N-1) (j=0 to N-1) This transform is normalized since a call to WCost1b followed by a call to WCost1f (or vice-versa) reproduces the original array subject to algorithmic constraints, roundoff error, etc. Returns N x 1 Column 1 Rows 1 to N Cosine backward transformed data sequence Parameters [in] N The length of the sequence to be transformed. (N >= 1) The transform is most efficient when N - 1 is a product of small primes. [in] R (N) The sequence to be transformed. Reference FFTPACK Example See example of WCost1f.