template < class Q1, class R1> BOOST_FORCEINLINE
void do_it(A0& a0, const char& orient, Q1 & q1, R1 & r1) const
{
BOOST_AUTO_TPL(q, boost::proto::child_c<0>(a0));
BOOST_AUTO_TPL(r, boost::proto::child_c<1>(a0));
size_t j = boost::proto::child_c<2>(a0);
BOOST_AUTO_TPL(x, boost::proto::child_c<3>(a0));
table<value_t, nt2::of_size_<2, 2> > g;
size_t n = size(r, 2);
size_t m = size(r, 1);
if (orient == 'c')
{
// Make room and insert x before j-th column.
r1.resize(nt2::of_size(m, n+1));
q1 = q;
r1(nt2::_,nt2::_(1, j-1)) = r(nt2::_,nt2::_(1, j-1));
r1(nt2::_,nt2::_(j+1, n+1)) = r(nt2::_,nt2::_(j, n));
r1(nt2::_,j) = nt2::mtimes(nt2::ct(q), x);
++n;
// now r has nonzeros below the diagonal in the j-th column,
// and "extra" zeros on the diagonal in later columns.
// r = [x x x x x [x x x x x
// 0 x x x x g 0 x x x x
// 0 0 + x x ---> 0 0 * * *
// 0 0 + 0 x 0 0 0 * *
// 0 0 + 0 0] 0 0 0 0 *]
// use givens rotations to zero the +'s, one at a time, from bottom to top.
//
// q is treated to (the transpose of) the same rotations.
// q = [x x x x x g' [x x * * *
// x x x x x ---> x x * * *
// x x x x x x x * * *
// x x x x x x x * * *
// x x x x x] x x * * *]
for(size_t k = m-1; k >= j; --k)
{
BOOST_AUTO_TPL(p, nt2::cons(k, k+1));
nt2::tie(g,r1(p,j)) = nt2::planerot(r1(p,j));
if (k < n)
{
r1(p,nt2::_(k+1, n)) = nt2::mtimes(g, r1(p,nt2::_(k+1, n)));
}
q1(nt2::_,p) = nt2::mtimes(q1(nt2::_,p), nt2::ct(g));
}
}
else
{
r1 = catv(x, r);
q1 = catv(cath(nt2::One<value_t>(), nt2::zeros(1,m,meta::as_<value_t>())),
cath(nt2::zeros(m,1,meta::as_<value_t>()),q));
// now r is upper hessenberg.
// r = [x x x x [* * * *
// + x x x g * * *
// + x x ---> * *
// + x *
// + 0 0 0 0
// 0 0 0 0 0 0 0 0
// 0 0 0 0] 0 0 0 0]
// use givens rotations to zero the +'s, one at a time, from top to bottom.
//
// q is treated to (the transpose of) the same rotations and then a row
// permutation, p, to shuffle row 1 down to row j.
// q = [1 | 0 0 0 0 0 [# # # # # # [* * * * * *
// --|---------- ----------- -----------
// 0 | x x x x x g' * * * * * * p * * * * * *
// 0 | x x x x x ---> * * * * * * ---> # # # # # #
// 0 | x x x x x * * * * * * * * * * * *
// 0 | x x x x x * * * * * * * * * * * *
// 0 | x x x x x] * * * * * *] * * * * * *]
for(size_t i = 1; i <= nt2::min(m,n); ++i)
{
BOOST_AUTO_TPL(p, nt2::cons(i, i+1));
nt2::tie(g,r1(p,i)) = nt2::planerot(r1(p,i));
r1(p,nt2::_(i+1, n)) = nt2::mtimes(g, r1(p,nt2::_(i+1, n)));
q1(nt2::_,p) = nt2::mtimes(q1(nt2::_,p), nt2::ct(g));
}
// this permutes row 1 of q*r to row j of q(p,:)*r
if (j != 1)
{
BOOST_AUTO_TPL(p, nt2::cath(nt2::cath(nt2::_(size_t(2), j), size_t(1)), nt2::_(j+1, m+1)));
table<value_t> qq = q1(p,nt2::_);
q1 = qq;
}
}
}
