r1mpyq.h

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// IWYU pragma: private
#include "./InternalHeaderCheck.h"
 
namespace Eigen {
 
namespace internal {
 
// TODO : move this to GivensQR once there's such a thing in Eigen
 
template <typename Scalar>
void r1mpyq(DenseIndex m, DenseIndex n, Scalar *a, const std::vector<JacobiRotation<Scalar> > &v_givens,
            const std::vector<JacobiRotation<Scalar> > &w_givens) {
  typedef DenseIndex Index;
 
  /*     apply the first set of givens rotations to a. */
  for (Index j = n - 2; j >= 0; --j)
    for (Index i = 0; i < m; ++i) {
      Scalar temp = v_givens[j].c() * a[i + m * j] - v_givens[j].s() * a[i + m * (n - 1)];
      a[i + m * (n - 1)] = v_givens[j].s() * a[i + m * j] + v_givens[j].c() * a[i + m * (n - 1)];
      a[i + m * j] = temp;
    }
  /*     apply the second set of givens rotations to a. */
  for (Index j = 0; j < n - 1; ++j)
    for (Index i = 0; i < m; ++i) {
      Scalar temp = w_givens[j].c() * a[i + m * j] + w_givens[j].s() * a[i + m * (n - 1)];
      a[i + m * (n - 1)] = -w_givens[j].s() * a[i + m * j] + w_givens[j].c() * a[i + m * (n - 1)];
      a[i + m * j] = temp;
    }
}
 
}  // end namespace internal
 
}  // end namespace Eigen