1 namespace Eigen {
2 
3 namespace internal {
4 
5 // TODO : move this to GivensQR once there's such a thing in Eigen
6 
7 template <typename Scalar>
r1mpyq(DenseIndex m,DenseIndex n,Scalar * a,const std::vector<JacobiRotation<Scalar>> & v_givens,const std::vector<JacobiRotation<Scalar>> & w_givens)8 void r1mpyq(DenseIndex m, DenseIndex n, Scalar *a, const std::vector<JacobiRotation<Scalar> > &v_givens, const std::vector<JacobiRotation<Scalar> > &w_givens)
9 {
10     typedef DenseIndex Index;
11 
12     /*     apply the first set of givens rotations to a. */
13     for (Index j = n-2; j>=0; --j)
14         for (Index i = 0; i<m; ++i) {
15             Scalar temp = v_givens[j].c() * a[i+m*j] - v_givens[j].s() * a[i+m*(n-1)];
16             a[i+m*(n-1)] = v_givens[j].s() * a[i+m*j] + v_givens[j].c() * a[i+m*(n-1)];
17             a[i+m*j] = temp;
18         }
19     /*     apply the second set of givens rotations to a. */
20     for (Index j = 0; j<n-1; ++j)
21         for (Index i = 0; i<m; ++i) {
22             Scalar temp = w_givens[j].c() * a[i+m*j] + w_givens[j].s() * a[i+m*(n-1)];
23             a[i+m*(n-1)] = -w_givens[j].s() * a[i+m*j] + w_givens[j].c() * a[i+m*(n-1)];
24             a[i+m*j] = temp;
25         }
26 }
27 
28 } // end namespace internal
29 
30 } // end namespace Eigen
31