### 9.3 Accessing permutation elements

The following functions can be used to access and manipulate permutations.

Function: size_t gsl_permutation_get (const gsl_permutation * p, const size_t i)

  This function returns the value of the i-th element of the permutation p. If i lies outside the allowed range of 0 to n-1 then the error handler is invoked and 0 is returned. An inline version of this function is used when `HAVE_INLINE` is defined.

Function: int gsl_permutation_swap (gsl_permutation * p, const size_t i, const size_t j)

  This function exchanges the i-th and j-th elements of the permutation p.