action_on_k_subsets.cpp

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// action_on_k_subsets.cpp
//
// Anton Betten
// May 15, 2012
 
#include "foundations/foundations.h"
#include "group_actions.h"
 
using namespace std;
 
 
namespace orbiter {
namespace layer3_group_actions {
namespace induced_actions {
 
 
action_on_k_subsets::action_on_k_subsets()
{
    null();
}
 
action_on_k_subsets::~action_on_k_subsets()
{
    free();
}
 
void action_on_k_subsets::null()
{
    A = NULL;
    set1 = NULL;
    set2 = NULL;
}
 
void action_on_k_subsets::free()
{
    if (set1) {
        FREE_int(set1);
        }
    if (set2) {
        FREE_int(set2);
        }
    null();
}
 
void action_on_k_subsets::init(actions::action *A,
        int k, int verbose_level)
{
    int f_v = (verbose_level >= 1);
    int n;
    combinatorics::combinatorics_domain Combi;
    
    if (f_v) {
        cout << "action_on_k_subsets::init k=" << k << endl;
        }
    action_on_k_subsets::A = A;
    action_on_k_subsets::k = k;
    n = A->degree;
    degree = Combi.int_n_choose_k(n, k);
    set1 = NEW_int(k);
    set2 = NEW_int(k);
    if (f_v) {
        cout << "action_on_k_subsets::init n=" << n << endl;
        cout << "action_on_k_subsets::init "
                "n choose k=" << degree << endl;
        }
}
 
long int action_on_k_subsets::compute_image(
        int *Elt, long int i, int verbose_level)
{
    long int u, a, b, j;
    int f_v = (verbose_level >= 1);
    int f_vv = (verbose_level >= 2);
    combinatorics::combinatorics_domain Combi;
    data_structures::sorting Sorting;
 
    if (f_v) {
        cout << "action_on_k_subsets::compute_image "
                "i = " << i << endl;
        }
    if (i < 0 || i >= degree) {
        cout << "action_on_k_subsets::compute_image "
                "i = " << i << " out of range" << endl;
        exit(1);
        }
    Combi.unrank_k_subset(i, set1, A->degree, k);
    for (u = 0; u < k; u++) {
        a = set1[u];
        b = A->image_of(Elt, a);
        set2[u] = b;
        }
    Sorting.int_vec_heapsort(set2, k);
    j = Combi.rank_k_subset(set2, A->degree, k);
    if (f_vv) {
        cout << "set " << i << " = ";
        Int_vec_print(cout, set1, k);
        cout << " maps to ";
        Int_vec_print(cout, set2, k);
        cout << " = " << j << endl;
        }
    if (j < 0 || j >= degree) {
        cout << "action_on_k_subsets::compute_image "
                "j = " << j << " out of range" << endl;
        exit(1);
        }
    return j;
}
 
 
}}}