text: #ifndef KISS_FTR_H
  #define KISS_FTR_H
  
  #include "kiss_fft.h"
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /* 
   
   Real optimized version can save about 45% cpu time vs. complex fft of a real seq.
  
   
   
   */
  
  typedef struct kiss_fftr_state *kiss_fftr_cfg;
  
  kiss_fftr_cfg kiss_fftr_alloc(int nfft, int inverse_fft, void *mem, size_t *lenmem);
  /*
   nfft must be even
  
   If you don't care to allocate space, use mem = lenmem = NULL 
  */
  
  void kiss_fftr(kiss_fftr_cfg cfg, const kiss_fft_scalar *timedata, kiss_fft_cpx *freqdata);
  /*
   input timedata has nfft scalar points
   output freqdata has nfft/2+1 complex points
  */
  
  void kiss_fftri(kiss_fftr_cfg cfg, const kiss_fft_cpx *freqdata, kiss_fft_scalar *timedata);
  /*
   input freqdata has  nfft/2+1 complex points
   output timedata has nfft scalar points
  */
  
  #define kiss_fftr_free free
  
  #ifdef __cplusplus
  }
  #endif
  #endif
  