## Combination properties

Function: size_t gsl_combination_n (const gsl_combination * c)
  This function returns the n parameter of the combination c.

Function: size_t gsl_combination_k (const gsl_combination * c)
  This function returns the k parameter of the combination c.

Function: size_t * gsl_combination_data (const gsl_combination * c)
  This function returns a pointer to the array of elements in the combination c.

Function: int gsl_combination_valid (gsl_combination * c)
  This function checks that the combination c is valid. The k elements should contain numbers from range 0 .. n-1, each number at most once. The numbers have to be in increasing order.