void SMat<CoeffRing>::vec_set_entry(sparsevec *&v,
size_t r,
const elem &a) const
{
sparsevec *p;
bool iszero = ring().is_zero(a);
sparsevec head;
head.next = v;
for (p = &head; p->next != 0; p = p->next)
if (p->next->row <= r) break;
if (p->next == 0 || p->next->row < r)
{
if (iszero) return;
sparsevec *w = vec_new();
w->next = p->next;
w->row = r;
ring().init_set(w->coeff, a);
p->next = w;
}
else if (p->next->row == r)
{
if (iszero)
{
// delete node
sparsevec *tmp = p->next;
p->next = tmp->next;
vec_remove_node(tmp);
}
else
ring().set(p->next->coeff, a);
}
v = head.next;
}
void SMat<CoeffRing>::vec_remove(sparsevec *&v) const
{
while (v != 0)
{
sparsevec *tmp = v;
v = v->next;
vec_remove_node(tmp);
}
}
void SMat<CoeffRing>::vec_row_op(sparsevec *&v,
size_t r1,
const elem &a,
size_t r2) const
// row(r1 in v) := row(r1 in v) + a * row(r2 in v)
{
sparsevec *p;
sparsevec *vec2 = 0;
for (p = v; p != 0; p = p->next)
if (p->row == r2)
{
vec2 = p;
break;
}
if (vec2 == 0) return;
elem c;
ring().init(c);
ring().set_zero(c);
ring().mult(c, vec2->coeff, a);
if (ring().is_zero(c)) return; // nothing to change
// Now add c to the r1'th row of v
sparsevec head;
head.next = v;
for (p = &head; p->next != 0; p = p->next)
if (p->next->row <= r1) break;
if (p->next == 0 || p->next->row < r1)
{
// Make a new node
sparsevec *w = vec_new();
w->next = p->next;
w->row = r1;
ring().init_set(w->coeff, c);
p->next = w;
}
else
{
ring().add(p->next->coeff, p->next->coeff, c);
if (ring().is_zero(p->next->coeff))
{
sparsevec *tmp = p->next;
p->next = tmp->next;
vec_remove_node(tmp);
}
}
v = head.next;
ring().clear(c);
}
void SMat<CoeffRing>::vec_divide_row(sparsevec *&v, size_t r, const elem &a) const
{
sparsevec head;
head.next = v;
for (sparsevec *p = &head; p->next != 0; p = p->next)
if (p->next->row < r)
break;
else if (p->next->row == r)
{
ring().divide(p->next->coeff, p->next->coeff, a);
if (ring().is_zero(p->next->coeff))
{
sparsevec *tmp = p->next;
p->next = tmp->next;
vec_remove_node(tmp);
}
break;
}
v = head.next;
}
void SMat<CoeffRing>::vec_delete_rows(sparsevec *&v, size_t i, size_t j) const
{
size_t n_to_delete = j - i + 1;
sparsevec head;
sparsevec *w = &head;
w->next = v;
while (w->next != 0 && w->next->row >= i)
if (w->next->row <= j)
{
// this row is up for the chopping block
sparsevec *tmp = w->next;
w->next = tmp->next;
vec_remove_node(tmp);
}
else
{
w = w->next;
w->row -= n_to_delete;
}
v = head.next;
}
void SMat<CoeffRing>::vec_divide(sparsevec *&v, const elem &a) const
{
if (ring().is_zero(a))
{
vec_remove(v);
v = 0;
return;
}
sparsevec head;
head.next = v;
for (sparsevec *p = &head; p->next != 0; p = p->next)
{
ring().divide(p->next->coeff, p->next->coeff, a);
if (ring().is_zero(p->next->coeff))
{
sparsevec *tmp = p->next;
p->next = tmp->next;
vec_remove_node(tmp);
if (p->next == 0) break;
}
}
v = head.next;
}
void SMat<CoeffRing>::vec_add_to(sparsevec *&v, sparsevec *&w) const
// v := v+w, w := 0
{
if (w == 0) return;
if (v == 0)
{
v = w;
w = 0;
return;
}
sparsevec head;
sparsevec *result = &head;
while (true)
if (v->row < w->row)
{
result->next = w;
result = result->next;
w = w->next;
if (w == 0)
{
result->next = v;
v = head.next;
return;
}
}
else if (v->row > w->row)
{
result->next = v;
result = result->next;
v = v->next;
if (v == 0)
{
result->next = w;
v = head.next;
w = 0;
return;
}
}
else
{
sparsevec *tmv = v;
sparsevec *tmw = w;
v = v->next;
w = w->next;
ring().add(tmv->coeff, tmv->coeff, tmw->coeff);
if (ring().is_zero(tmv->coeff))
{
vec_remove_node(tmv);
}
else
{
result->next = tmv;
result = result->next;
}
vec_remove_node(tmw);
if (w == 0)
{
result->next = v;
v = head.next;
return;
}
if (v == 0)
{
result->next = w;
v = head.next;
w = 0;
return;
}
}
}
