// constants
static const double a1 = 0.7071067811865474; // sqrt(2)
static const double a2 = 0.5411961001461971; // cos(3/8 pi) * sqrt(2)
// constants
static const double a1 = 0.7071067811865474; // sqrt(2)
static const double a2 = 0.5411961001461971; // cos(3/8 pi) * sqrt(2)