syz4.cc File Reference

#include "kernel/GBEngine/syz.h"
#include "coeffs/numbers.h"
#include "kernel/polys.h"
#include "kernel/ideals.h"
#include <vector>
#include <map>

Go to the source code of this file.

Data Structures
struct	lt_struct
struct	cache_compare

Macros
#define	insert_first_term(r, p, q, R)

Typedefs
typedef std::map< poly, poly, cache_compare >	cache_term
typedef poly	syzHeadFunction(ideal, int, int)
typedef ideal	syzM_i_Function(ideal, int, syzHeadFunction)

Functions
static void	update_variables (std::vector< bool > &variables, const ideal L)
static bool	check_variables (const std::vector< bool > &variables, const poly m)
static void	initialize_hash (lt_struct **C, const ideal L)
static poly	find_reducer (const poly multiplier, const poly t, const lt_struct *const *const hash_previous_module)
static poly	traverse_tail (const poly multiplier, const int comp, const ideal previous_module, const std::vector< bool > &variables, const lt_struct *const *const hash_previous_module)
static poly	compute_image (const poly multiplier, const int comp, const ideal previous_module, const std::vector< bool > &variables, const lt_struct *const *const hash_previous_module, const bool use_cache)
static poly	reduce_term (const poly multiplier, const poly term, const ideal previous_module, const std::vector< bool > &variables, const lt_struct *const *const hash_previous_module, const bool use_cache)
static void	initialize_cache (const int size)
static void	delete_cache (const int size)
static void	insert_into_cache_term (cache_term *T, const poly multiplier, const poly p)
static poly	get_from_cache_term (const cache_term::const_iterator itr, const poly multiplier)
static poly	lift_ext_LT (const poly a, const ideal previous_module, const std::vector< bool > &variables, const lt_struct *const *const hash_previous_module, const bool use_cache)
static poly	syzHeadFrame (const ideal G, const int i, const int j)
static poly	syzHeadExtFrame (const ideal G, const int i, const int j)
static ideal	syzM_i_unsorted (const ideal G, const int i, syzHeadFunction *syzHead)
static ideal	syzM_i_sorted (const ideal G, const int i, syzHeadFunction *syzHead)
static ideal	idConcat (const ideal *M, const int size, const int rank)
static int	compare_comp (const poly p_a, const poly p_b)
static int	compare_deg (const poly p_a, const poly p_b)
static int	compare_lex (const poly p_a, const poly p_b)
static int	compare_Mi (const void *a, const void *b)
static ideal	computeFrame (const ideal G, syzM_i_Function syzM_i, syzHeadFunction *syzHead)
static void	computeLiftings (const resolvente res, const int index, const std::vector< bool > &variables, const bool use_cache)
static bool	contains_unused_variable (const poly m, const std::vector< bool > &variables)
static void	delete_variables (resolvente res, const int index, const std::vector< bool > &variables)
static void	delete_tails (resolvente res, const int index)
static int	computeResolution_iteration (resolvente res, const int max_index, syzHeadFunction *syzHead, const bool do_lifting, const bool single_module, const bool use_cache, const bool use_tensor_trick, std::vector< bool > &variables)
static int	computeResolution (resolvente res, const int max_index, syzHeadFunction *syzHead, const bool do_lifting, const bool single_module, const bool use_cache, const bool use_tensor_trick)
static void	set_options (syzHeadFunction **syzHead_ptr, bool *do_lifting_ptr, bool *single_module_ptr, const char *method)
static void	insert_ext_induced_LTs (const resolvente res, const int length, const bool single_module)
syStrategy	syFrank (const ideal arg, const int length, const char *method, const bool use_cache, const bool use_tensor_trick)

Variables
STATIC_VAR cache_term *	Cache

---

Data Structure Documentation

lt_struct

struct lt_struct

Definition at line 74 of file syz4.cc.

Data Fields
unsigned long	comp
poly	lt
unsigned long	sev

Macro Definition Documentation

insert_first_term

#define insert_first_term	(		r,
			p,
			q,
			R
	)

Value:

do                                                                \
{                                                                 \
    p = r;                                                        \
    q = p->next;                                                  \
    if (q != NULL && p_LmCmp(p, q, R) != 1) {                     \
        while (q->next != NULL && p_LmCmp(p, q->next, R) == -1) { \
            pIter(q);                                             \
        }                                                         \
        r = p->next;                                              \
        p->next = q->next;                                        \
        q->next = p;                                              \
    }                                                             \
}                                                                 \
while (0)

Definition at line 738 of file syz4.cc.

Typedef Documentation

cache_term

typedef std::map<poly, poly, cache_compare> cache_term

Definition at line 228 of file syz4.cc.

syzHeadFunction

typedef poly syzHeadFunction(ideal, int, int)

Definition at line 321 of file syz4.cc.

syzM_i_Function

typedef ideal syzM_i_Function(ideal, int, syzHeadFunction)

Definition at line 377 of file syz4.cc.

Function Documentation

check_variables()

static bool check_variables ( const std::vector< bool > &  variables, const poly  m  )

inlinestatic

Definition at line 49 of file syz4.cc.

{
    const ring R = currRing;
    // variables[R->N] is true iff index == 1, that is, for the first step in
    // the resolution
    if (UNLIKELY(variables[R->N]))
    {
        return true;
    }
    for (int j = R->N; j > 0; j--)
    {
        if (UNLIKELY(variables[j-1] && p_GetExp(m, j, R) > 0))
        {
            return true;
        }
    }
    return false;
}

compare_comp()

static int compare_comp ( const poly  p_a, const poly  p_b  )

static

Definition at line 471 of file syz4.cc.

{
    const ring r = currRing;
    long comp_a = __p_GetComp(p_a, r);
    long comp_b = __p_GetComp(p_b, r);
    return (comp_a > comp_b) - (comp_a < comp_b);
}

compare_deg()

static int compare_deg ( const poly  p_a, const poly  p_b  )

static

Definition at line 479 of file syz4.cc.

{
    const ring r = currRing;
    long deg_a = p_Deg(p_a, r);
    long deg_b = p_Deg(p_b, r);
    return (deg_a > deg_b) - (deg_a < deg_b);
}

compare_lex()

static int compare_lex ( const poly  p_a, const poly  p_b  )

static

Definition at line 487 of file syz4.cc.

{
    int cmp;
    const ring r = currRing;
    int exp_a[r->N+1];
    int exp_b[r->N+1];
    p_GetExpV(p_a, exp_a, r);
    p_GetExpV(p_b, exp_b, r);
    for (int i = r->N; i > 0; i--)
    {
        cmp = (exp_a[i] > exp_b[i]) - (exp_a[i] < exp_b[i]);
        if (cmp != 0)
        {
            return cmp;
        }
    }
    return 0;
}

compare_Mi()

static int compare_Mi ( const void *  a, const void *  b  )

static

Definition at line 506 of file syz4.cc.

{
    poly p_a = *((poly *)a);
    poly p_b = *((poly *)b);
    int cmp;
    if ((cmp = compare_comp(p_a, p_b))
            || (cmp = compare_deg(p_a, p_b))
            || (cmp = compare_lex(p_a, p_b)))
            {
        return cmp;
    }
    return 0;
}

compute_image()

static poly compute_image ( const poly  multiplier, const int  comp, const ideal  previous_module, const std::vector< bool > &  variables, const lt_struct *const *const  hash_previous_module, const bool  use_cache  )

static

Definition at line 192 of file syz4.cc.

{
    const poly tail = previous_module->m[comp]->next;
    if (UNLIKELY(tail == NULL) || !check_variables(variables, multiplier))
    {
        return NULL;
    }
    sBucket_pt sum = sBucketCreate(currRing);
    for (poly p = tail; p != NULL; p = pNext(p))
    {
        const poly rt = reduce_term(multiplier, p, previous_module, variables,
                hash_previous_module, use_cache);
        sBucket_Add_p(sum, rt, pLength(rt));
    }
    poly s;
    int l;
    sBucketClearAdd(sum, &s, &l);
    sBucketDestroy(&sum);
    return s;
}

computeFrame()

static ideal computeFrame ( const ideal  G, syzM_i_Function  syzM_i, syzHeadFunction *  syzHead  )

static

Definition at line 524 of file syz4.cc.

{
    ideal *M = (ideal *)omalloc((G->ncols-1)*sizeof(ideal));
    for (int i = G->ncols-2; i >= 0; i--)
    {
        M[i] = syzM_i(G, i+1, syzHead);
    }
    ideal frame = idConcat(M, G->ncols-1, G->ncols);
    for (int i = G->ncols-2; i >= 0; i--)
    {
        if (M[i] != NULL)
        {
            omFreeSize(M[i]->m, M[i]->ncols*sizeof(poly));
            omFreeBin(M[i], sip_sideal_bin);
        }
    }
    omfree(M);
    qsort(frame->m, frame->ncols, sizeof(poly), compare_Mi);
    return frame;
}

computeLiftings()

static void computeLiftings ( const resolvente  res, const int  index, const std::vector< bool > &  variables, const bool  use_cache  )

static

Definition at line 549 of file syz4.cc.

{
    if (use_cache)
    {
        initialize_cache(res[index-1]->ncols);
    }
    lt_struct **hash_previous_module
        = (lt_struct **)omAlloc((res[index-1]->rank+1)*sizeof(lt_struct *));
    initialize_hash(hash_previous_module, res[index-1]);
    for (int j = res[index]->ncols-1; j >= 0; j--)
    {
        res[index]->m[j]->next->next = lift_ext_LT(res[index]->m[j],
                res[index-1], variables, hash_previous_module, use_cache);
    }
    for (int i = 0; i <= res[index-1]->rank; i++)
    {
        omfree(hash_previous_module[i]);
    }
    omFree(hash_previous_module);
    if (use_cache)
    {
        delete_cache(res[index-1]->ncols);
    }
}

computeResolution()

static int computeResolution ( resolvente  res, const int  max_index, syzHeadFunction *  syzHead, const bool  do_lifting, const bool  single_module, const bool  use_cache, const bool  use_tensor_trick  )

static

Definition at line 670 of file syz4.cc.

{
    if (idIs0(res[0]))
    {
        return 1;
    }
    std::vector<bool> variables;
    variables.resize(currRing->N+1, true);
    if (do_lifting)
    {
        update_variables(variables, res[0]);
        if (use_tensor_trick)
        {
            delete_variables(res, 0, variables);
        }
    }
    int index = 0;
    if (max_index > 0)
    {
        res[1] = computeFrame(res[0], syzM_i_unsorted, syzHead);
        index = computeResolution_iteration(res, max_index, syzHead,
                do_lifting, single_module, use_cache, use_tensor_trick,
                variables);
    }
    variables.clear();
    return index+1;
}

computeResolution_iteration()

static int computeResolution_iteration ( resolvente  res, const int  max_index, syzHeadFunction *  syzHead, const bool  do_lifting, const bool  single_module, const bool  use_cache, const bool  use_tensor_trick, std::vector< bool > &  variables  )

static

Definition at line 633 of file syz4.cc.

{
    int index = 1;
    while (!idIs0(res[index]))
    {
        if (do_lifting)
        {
            computeLiftings(res, index, variables, use_cache);
            if (single_module)
            {
                delete_tails(res, index-1);
            }
            // we don't know if the input is a reduced SB:
            if (index == 1)
            {
                variables[currRing->N] = false;
            }
            update_variables(variables, res[index]);
            if (use_tensor_trick)
            {
                delete_variables(res, index, variables);
            }
        }
        if (index >= max_index) { break; }
        index++;
        res[index] = computeFrame(res[index-1], syzM_i_sorted, syzHead);
    }
    return index;
}

contains_unused_variable()

static bool contains_unused_variable ( const poly  m, const std::vector< bool > &  variables  )

inlinestatic

Definition at line 578 of file syz4.cc.

{
    const ring R = currRing;
    for (int j = R->N; j > 0; j--)
    {
        if (!variables[j-1] && p_GetExp(m, j, R) > 0)
        {
            return true;
        }
    }
    return false;
}

delete_cache()

static void delete_cache ( const int  size )

static

Definition at line 237 of file syz4.cc.

{
    const ring r = currRing;
    for (int i = 0; i < size; i++)
    {
        cache_term *T = &(Cache[i]);
        for (cache_term::iterator itr = T->begin(); itr != T->end(); ++itr)
        {
            p_Delete(&(itr->second), r);
            p_Delete(const_cast<poly*>(&(itr->first)), r);
        }
        T->clear();
    }
    delete[](Cache);
}

delete_tails()

static void delete_tails ( resolvente  res, const int  index  )

static

Definition at line 617 of file syz4.cc.

{
    const ring r = currRing;
    for (int i = 0; i < res[index]->ncols; i++)
    {
        if (res[index]->m[i] != NULL)
        {
            p_Delete(&(res[index]->m[i]->next), r);
        }
    }
}

delete_variables()

static void delete_variables ( resolvente  res, const int  index, const std::vector< bool > &  variables  )

static

Definition at line 596 of file syz4.cc.

{
    for (int i = 0; i < res[index]->ncols; i++)
    {
        poly p_iter = res[index]->m[i]->next;
        if (p_iter != NULL)
        {
            while (p_iter->next != NULL)
            {
                if (contains_unused_variable(p_iter->next, variables))
                {
                    pLmDelete(&p_iter->next);
                } else {
                    pIter(p_iter);
                }
            }
        }
    }
}

find_reducer()

static poly find_reducer ( const poly  multiplier, const poly  t, const lt_struct *const *const  hash_previous_module  )

static

Definition at line 118 of file syz4.cc.

{
    const ring r = currRing;
    const lt_struct *v = hash_previous_module[__p_GetComp(t, r)];
    unsigned long count = v[0].comp;
    if (UNLIKELY(count == 1))
    {
        return NULL;
    }
    const poly q = p_New(r);
    pNext(q) = NULL;
    p_MemSum_LengthGeneral(q->exp, multiplier->exp, t->exp, r->ExpL_Size);
    const unsigned long q_not_sev = ~p_GetShortExpVector(q, r);
    for(unsigned long i = 1; i < count; i++)
    {
        if (LIKELY(v[i].sev & q_not_sev)
                || UNLIKELY(!(_p_LmDivisibleByNoComp(v[i].lt, q, r))))
                {
            continue;
        }
        p_MemAdd_NegWeightAdjust(q, r);
        p_ExpVectorDiff(q, q, v[i].lt, r);
        p_SetComp(q, v[i].comp, r);
        p_Setm(q, r);
        number n = n_Div(p_GetCoeff(multiplier, r), p_GetCoeff(v[i].lt, r), r->cf);
        n_InpMult(n, p_GetCoeff(t, r), r->cf);
        p_SetCoeff0(q, n_InpNeg(n, r->cf), r);
        return q;
    }
    p_LmFree(q, r);
    return NULL;
}

get_from_cache_term()

static poly get_from_cache_term ( const cache_term::const_iterator  itr, const poly  multiplier  )

static

Definition at line 260 of file syz4.cc.

{
    if (LIKELY(itr->second == NULL))
    {
        return NULL;
    }
    const ring r = currRing;
    poly p = p_Copy(itr->second, r);
    if (LIKELY(!n_Equal(pGetCoeff(multiplier), pGetCoeff(itr->first), r->cf)))
    {
        number n = n_Div(pGetCoeff(multiplier), pGetCoeff(itr->first), r->cf);
        p = p_Mult_nn(p, n, r);
        n_Delete(&n, r->cf);
    }
    return p;
}

idConcat()

static ideal idConcat ( const ideal *  M, const int  size, const int  rank  )

static

Definition at line 444 of file syz4.cc.

{
    int ncols = 0;
    for (int i = size-1; i >= 0; i--)
    {
        if (M[i] != NULL)
        {
            ncols += M[i]->ncols;
        }
    }
    if (ncols == 0) return idInit(1, rank);
    ideal result = idInit(ncols, rank);
    int k = ncols-1;
    for (int i = size-1; i >= 0; i--)
    {
        if (M[i] != NULL)
        {
            for (int j = M[i]->ncols-1; j >= 0; j--)
            {
                result->m[k] = M[i]->m[j];
                k--;
            }
        }
    }
    return result;
}

initialize_cache()

static void initialize_cache ( const int  size )

static

Definition at line 232 of file syz4.cc.

{
    Cache = new cache_term[size];
}

initialize_hash()

static void initialize_hash ( lt_struct **  C, const ideal  L  )

static

Definition at line 80 of file syz4.cc.

{
    const ring R = currRing;
    const unsigned long n_elems = L->ncols;
    unsigned int *count
        = (unsigned int *)omAlloc0((L->rank+1)*sizeof(unsigned int));
    unsigned long k = 0;
    while (k < n_elems)
    {
        count[__p_GetComp(L->m[k], R)]++;
        k++;
    }
    for (int i = 0; i <= L->rank; i++)
    {
        // do ++count[i] and use C[i][0].comp to save count[i]
        C[i] = (lt_struct *)omalloc0((++count[i])*sizeof(lt_struct));
        C[i][0].comp = count[i];
    }
    k = n_elems;
    // the order of the elements in each C[i] matters if check_variables() is
    // to be used
    while (k > 0)
    {
        const poly a = L->m[k-1];
        const unsigned long comp = __p_GetComp(a, R);
        C[comp][--count[comp]]
            = (lt_struct){a, p_GetShortExpVector(a, R), k};
        k--;
    }
    omFree(count);
}

insert_ext_induced_LTs()

static void insert_ext_induced_LTs ( const resolvente  res, const int  length, const bool  single_module  )

static

Definition at line 758 of file syz4.cc.

{
    const ring R = currRing;
    poly p, q;
    int index = (single_module ? length-1 : 1);
    while (index < length && !idIs0(res[index]))
    {
        for (int j = res[index]->ncols-1; j >= 0; j--)
        {
            insert_first_term(res[index]->m[j]->next, p, q, R);
            insert_first_term(res[index]->m[j], p, q, R);
        }
        index++;
    }
}

insert_into_cache_term()

static void insert_into_cache_term ( cache_term *  T, const poly  multiplier, const poly  p  )

static

Definition at line 253 of file syz4.cc.

{
    const ring r = currRing;
    T->insert(cache_term::value_type(p_Head(multiplier, r), p_Copy(p, r)));
}

lift_ext_LT()

static poly lift_ext_LT ( const poly  a, const ideal  previous_module, const std::vector< bool > &  variables, const lt_struct *const *const  hash_previous_module, const bool  use_cache  )

static

Definition at line 297 of file syz4.cc.

{
    const ring R = currRing;
    // the leading term does not need to be cached
    poly t1 = compute_image(a, __p_GetComp(a, R)-1, previous_module, variables,
            hash_previous_module, use_cache);
    poly t2;
    if (use_cache)
    {
        t2 = traverse_tail(a->next, __p_GetComp(a->next, R)-1,
                previous_module, variables, hash_previous_module);
    } else {
        t2 = compute_image(a->next, __p_GetComp(a->next, R)-1,
                previous_module, variables, hash_previous_module, false);
    }
    t1 = p_Add_q(t1, t2, R);
    return t1;
}

reduce_term()

static poly reduce_term ( const poly  multiplier, const poly  term, const ideal  previous_module, const std::vector< bool > &  variables, const lt_struct *const *const  hash_previous_module, const bool  use_cache  )

static

Definition at line 164 of file syz4.cc.

{
    poly s = find_reducer(multiplier, term, hash_previous_module);
    if (s == NULL)
    {
        return NULL;
    }
    const ring r = currRing;
    const int c = __p_GetComp(s, r) - 1;
    poly t;
    if (use_cache)
    {
        t = traverse_tail(s, c, previous_module, variables,
                hash_previous_module);
    } else {
        t = compute_image(s, c, previous_module, variables,
                hash_previous_module, false);
    }
    return p_Add_q(s, t, r);
}

set_options()

static void set_options ( syzHeadFunction **  syzHead_ptr, bool *  do_lifting_ptr, bool *  single_module_ptr, const char *  method  )

static

Definition at line 701 of file syz4.cc.

{
    if (strcmp(method, "complete") == 0)
    {   // default
        *syzHead_ptr = syzHeadExtFrame;
        *do_lifting_ptr = true;
        *single_module_ptr = false;
    }
    else if (strcmp(method, "frame") == 0)
    {
        *syzHead_ptr = syzHeadFrame;
        *do_lifting_ptr = false;
        *single_module_ptr = false;
    }
    else if (strcmp(method, "extended frame") == 0)
    {
        *syzHead_ptr = syzHeadExtFrame;
        *do_lifting_ptr = false;
        *single_module_ptr = false;
    }
    else if (strcmp(method, "single module") == 0)
    {
        *syzHead_ptr = syzHeadExtFrame;
        *do_lifting_ptr = true;
        *single_module_ptr = true;
    }
    else {   // "linear strand" (not yet implemented)
        *syzHead_ptr = syzHeadExtFrame;
        *do_lifting_ptr = true;
        *single_module_ptr = false;
    }
}

syFrank()

syStrategy syFrank	(	const ideal	arg,
		const int	length,
		const char *	method,
		const bool	use_cache,
		const bool	use_tensor_trick
	)

Definition at line 792 of file syz4.cc.

{
    syStrategy result = (syStrategy)omAlloc0(sizeof(ssyStrategy));
    resolvente res = (resolvente)omAlloc0((length+1)*sizeof(ideal));
    if (strcmp(method, "frame") != 0)
    {
        res[0] = id_Copy(arg, currRing);
    }
    else
    {
        res[0] = id_Head(arg, currRing);
    }
    syzHeadFunction *syzHead;
    bool do_lifting;
    bool single_module;
    set_options(&syzHead, &do_lifting, &single_module, method);
    int new_length = computeResolution(res, length-1, syzHead, do_lifting,
            single_module, use_cache, use_tensor_trick);
    if (new_length < length)
    {
        res = (resolvente)omReallocSize(res, (length+1)*sizeof(ideal),
                (new_length+1)*sizeof(ideal));
    }
    if (strcmp(method, "frame") != 0)
    {
        insert_ext_induced_LTs(res, new_length, single_module);
    }
    result->fullres = res;
    result->length = new_length;
    result->list_length = new_length;
    return result;
}

syzHeadExtFrame()

static poly syzHeadExtFrame ( const ideal  G, const int  i, const int  j  )

static

Definition at line 350 of file syz4.cc.

{
    const ring r = currRing;
    const poly f_i = G->m[i];
    const poly f_j = G->m[j];
    poly head = p_Init(r);
    pSetCoeff0(head, n_Init(1, r->cf));
    poly head_ext = p_Init(r);
    pSetCoeff0(head_ext, n_InpNeg(n_Div(pGetCoeff(f_i), pGetCoeff(f_j), r->cf),
                r->cf));
    long exp_i, exp_j, lcm;
    for (int k = (int)r->N; k > 0; k--)
    {
        exp_i = p_GetExp(f_i, k, r);
        exp_j = p_GetExp(f_j, k, r);
        lcm = si_max(exp_i, exp_j);
        p_SetExp(head, k, lcm-exp_i, r);
        p_SetExp(head_ext, k, lcm-exp_j, r);
    }
    p_SetComp(head, i+1, r);
    p_Setm(head, r);
    p_SetComp(head_ext, j+1, r);
    p_Setm(head_ext, r);
    head->next = head_ext;
    return head;
}

syzHeadFrame()

static poly syzHeadFrame ( const ideal  G, const int  i, const int  j  )

static

Definition at line 326 of file syz4.cc.

{
    const ring r = currRing;
    const poly f_i = G->m[i];
    const poly f_j = G->m[j];
    poly head = p_Init(r);
    pSetCoeff0(head, n_Init(1, r->cf));
    long exp_i, exp_j, lcm;
    for (int k = (int)r->N; k > 0; k--)
    {
        exp_i = p_GetExp(f_i, k, r);
        exp_j = p_GetExp(f_j, k, r);
        lcm = si_max(exp_i, exp_j);
        p_SetExp(head, k, lcm-exp_i, r);
    }
    p_SetComp(head, i+1, r);
    p_Setm(head, r);
    return head;
}

syzM_i_sorted()

static ideal syzM_i_sorted ( const ideal  G, const int  i, syzHeadFunction *  syzHead  )

static

Definition at line 418 of file syz4.cc.

{
    const ring r = currRing;
    ideal M_i = NULL;
    unsigned long comp = __p_GetComp(G->m[i], r);
    int index = i-1;
    while (__p_GetComp(G->m[index], r) == comp) index--;
    index++;
    int ncols = i-index;
    if (ncols > 0)
    {
        M_i = idInit(ncols, G->ncols);
        for (int j = ncols-1; j >= 0; j--)
        {
            M_i->m[j] = syzHead(G, i, j+index);
        }
        id_DelDiv(M_i, currRing);
        idSkipZeroes(M_i);
    }
    return M_i;
}

syzM_i_unsorted()

static ideal syzM_i_unsorted ( const ideal  G, const int  i, syzHeadFunction *  syzHead  )

static

Definition at line 384 of file syz4.cc.

{
    const ring r = currRing;
    ideal M_i = NULL;
    unsigned long comp = __p_GetComp(G->m[i], r);
    int ncols = 0;
    for (int j = i-1; j >= 0; j--)
    {
        if (__p_GetComp(G->m[j], r) == comp) ncols++;
    }
    if (ncols > 0)
    {
        M_i = idInit(ncols, G->ncols);
        int k = ncols-1;
        for (int j = i-1; j >= 0; j--)
        {
            if (__p_GetComp(G->m[j], r) == comp)
            {
                M_i->m[k] = syzHead(G, i, j);
                k--;
            }
        }
        id_DelDiv(M_i, currRing);
        idSkipZeroes(M_i);
    }
    return M_i;
}

traverse_tail()

static poly traverse_tail ( const poly  multiplier, const int  comp, const ideal  previous_module, const std::vector< bool > &  variables, const lt_struct *const *const  hash_previous_module  )

static

Definition at line 278 of file syz4.cc.

{
    cache_term *T = &(Cache[comp]);
    cache_term::const_iterator itr = T->find(multiplier);
    if (LIKELY(itr != T->end()))
    {
        return get_from_cache_term(itr, multiplier);
    }
    poly p = compute_image(multiplier, comp, previous_module, variables,
            hash_previous_module, true);
    insert_into_cache_term(T, multiplier, p);
    return p;
}

update_variables()

static void update_variables ( std::vector< bool > &  variables, const ideal  L  )

static

Definition at line 21 of file syz4.cc.

{
    const ring R = currRing;
    const int l = L->ncols-1;
    int k;
    for (int j = R->N; j > 0; j--)
    {
        if (variables[j-1])
        {
            for (k = l; k >= 0; k--)
            {
                if (p_GetExp(L->m[k], j, R) > 0)
                {
                    break;
                }
            }
            if (k < 0)
            {   // no break
                variables[j-1] = false;
            }
        }
    }
}

Variable Documentation

Cache

STATIC_VAR cache_term* Cache

Definition at line 230 of file syz4.cc.