perm.h – permutations¶
Memory management¶
-
slong *
_perm_init
(slong n)¶ Initialises the permutation for use.
-
void
_perm_clear
(slong *vec)¶ Clears the permutation.
Assignment¶
-
void
_perm_set
(slong *res, const slong *vec, slong n)¶ Sets the permutation
res
to the same as the permutationvec
.
-
void
_perm_set_one
(slong *vec, slong n)¶ Sets the permutation to the identity permutation.
-
void
_perm_inv
(slong *res, const slong *vec, slong n)¶ Sets
res
to the inverse permutation ofvec
. Allows aliasing ofres
andvec
.
Composition¶
-
void
_perm_compose
(slong *res, const slong *vec1, const slong *vec2, slong n)¶ Forms the composition \(\pi_1 \circ \pi_2\) of two permutations \(\pi_1\) and \(\pi_2\). Here, \(\pi_2\) is applied first, that is, \((\pi_1 \circ \pi_2)(i) = \pi_1(\pi_2(i))\).
Allows aliasing of
res
,vec1
andvec2
.
Parity¶
-
int
_perm_parity
(const slong *vec, slong n)¶ Returns the parity of
vec
, 0 if the permutation is even and 1 if the permutation is odd.