int quadratic_line_intersection(const double a, const double b, const double c,
const double d, const double e, const double f,
const Point_2& B, const Vector_2& V,
double t[2], Point_2 p_[2])
{
const double A_ = a*V.x()*V.x()+b*V.x()*V.y()+c*V.y()*V.y();
const double B_ = 2*a*B.x()*V.x()+b*(B.y()*V.x()+B.x()*V.y())+2*c*B.y()*V.y()+d*V.x()+e*V.y();
const double C_ = a*B.x()*B.x()+b*B.x()*B.y()+c*B.y()*B.y()+d*B.x()+e*B.y()+f;
int ret = quadratic(A_, B_, C_, t);
if (ret == 0) {
p_[0] = B + t[0]*V;
p_[1] = p_[0];
}
else if (ret == 1) {
p_[0] = B + t[0]*V;
p_[1] = B + t[1]*V;
}
return ret;
}
void load_fields_on_fft( const Triangulation& T , CH_FFT& fft ) {
int Nb = fft.Nx();
size_t align=fft.alignment();
c_array ux( Nb , Nb , align );
c_array uy( Nb , Nb , align );
for(F_v_it vit=T.vertices_begin();
vit != T.vertices_end();
vit++) {
int nx = vit->nx.val();
int ny = vit->ny.val();
// "right" ordering
int i = ( Nb - 1 ) - ny ;
int j = nx;
// "wrong" ordering
// int i = nx;
// int j = ny;
Vector_2 vv = vit->Uold.val();
//FT val = vit->alpha.val();
ux(i,j) = vv.x();
uy(i,j) = vv.y();
}
fft.set_u( ux , uy );
return;
}