kdata_xmean,
    kdata_ymean — compute
    arithmetic mean of data
#include <cairo.h>
  
  #include <kplot.h>
double
  
  kdata_xmean(const struct kdata
    *data);
double
  
  kdata_ymean(const struct kdata
    *data);
The kdata_xmean and
    kdata_ymean functions compute the arithmetic mean of
    a data source.
If the data source has zero entries,
    kdata_xmean and kdata_ymean
    return 0.0. Otherwise, they returns the mean value.