text: #include "sort.h"
  
  int compare_fractional_part(const void *vp, const void *vq)
  {
     const float   *p = vp, *q = vq;
     float         x;
  
     x = fractional_part(*p) - fractional_part(*q);
     return ((x < 0.0) ? -1 : (x == 0.0) ? 0 : +1);
  }
  
  int lexico(const void *vp, const void *vq)
  {
     const char   *p = vp, *q = vq;
     return (*p - *q);
  }
  