void L::initNiederreiter
(GeneratorMatrixGen<typename A::type> &gm, A a, int d,
const typename PolynomialRing<A>::type &irred)
{
typedef typename A::type T;
typedef PolynomialRing<A> PolyRing;
typedef typename PolyRing::type Poly;
const int degree = irred.degree ();
const int vSize
= std::max (gm.getM() + degree - 1, // these elements are copied to gm
(gm.getPrec() + degree + 1)); // used in the loop
Array<T> v (vSize);
PolyRing poly (a);
// cout << "Using " << irred << " for d=" << d << endl;
Poly newPoly = poly.one();
int u = 0;
for (int j = 0; j < gm.getPrec(); j++)
{
// cout << " j=" << j << endl;
// Do we need a new v?
if (u == 0)
{
Poly oldPoly = newPoly;
int oldDegree = oldPoly.degree ();
// calculate polyK+1 from polyK
poly.mulBy (newPoly, irred);
int newDegree = newPoly.degree ();
// cout << " newPolynomial: " << newPoly << endl;
// kj can be set to any value between 0 <= kj < newDegree
const int kj = oldDegree // proposed by BFN
// newDegree - 1 // standard, bad???
// 0
// (newDegree > 3) ? 3 : oldDegree
;
std::fill (&v[0], &v[kj], T()); // Set leading v's to 0
v[kj] = a.one(); // the next one is 1
if (kj < oldDegree)
{
T term = oldPoly [kj];
for (int r = kj + 1; r < oldDegree; ++r)
{
v [r] = a.one (); // 1 is arbitrary. Could be 0, too
a.addTo (term, a.mul (oldPoly [r], v [r]));
}
// set v[] not equal to -term
v [oldDegree] = a.sub (a.one(), term);
for (int r = oldDegree + 1; r < newDegree; ++r) v [r] = a.one(); //or 0
}
else
{
for (int r = kj + 1; r < newDegree; ++r) v [r] = a.one(); // or 0..
}
// All other elements are calculated by a recursion parameterized
// by polyK
for (int r = 0; r < vSize - newDegree; ++r)
{
T term = T();
for (int i = 0; i < newDegree; ++i)
{
a.addTo (term, a.mul (newPoly [i], v [r+i]));
}
v [newDegree + r] = a.neg (term);
}
}
// Set data in ci
for (int r = 0; r < gm.getM(); ++r) gm.setd (d,r,j, v[r+u]);
if (++u == degree) u = 0;
}
}
