### Equivalent of dormhr afer Schur decomposition

Posted:

**Thu Feb 01, 2018 4:40 am**Hi.

I see that dormhr can be used to apply orthogonal matrices (let's call them Q) coming from dgehrd (Hessenberg reduction) to given matrices. Then, dhseqr can follow dgehrd to compute the orthogonal matrix (let's call it Z, which contains Q as a factor) of a Schur decomposition. But how can I apply Z to given matrices? Shall I use the general dgemm? Thanks.

I see that dormhr can be used to apply orthogonal matrices (let's call them Q) coming from dgehrd (Hessenberg reduction) to given matrices. Then, dhseqr can follow dgehrd to compute the orthogonal matrix (let's call it Z, which contains Q as a factor) of a Schur decomposition. But how can I apply Z to given matrices? Shall I use the general dgemm? Thanks.