kdata_bucket_add
    kdata_bucket_set — modify
    bucket data values
#include <cairo.h>
  
  #include <kplot.h>
int
  
  kdata_bucket_add(struct kdata
    *d, size_t bucket, double
    y);
int
  
  kdata_bucket_set(struct kdata
    *d, size_t bucket, size_t
    x, double y);
The kdata_bucket_add and
    kdata_bucket_set set the x and
    y values to the position mapped from
    bucket after checking that
    bucket lies in the range provided to
    kdata_bucket_alloc(3).
kdata_bucket_add and
    kdata_bucket_set return 0 if the
    bucket is outside of the bucket range, the source was
    not created with
    kdata_bucket_alloc(3),
    or if any dependent sources fail. Otherwise it returns non-zero.