Reorders the Schur factorization of a general matrix.
p?trordreorders the real Schur factorization of a real matrix
T, so that a selected cluster of eigenvalues appears in the leading diagonal blocks of the upper quasi-triangular matrix
T, and the leading columns of
Qform an orthonormal basis of the corresponding right invariant subspace.
Tmust be in Schur form (as returned by
p?lahqr), that is, block upper triangular with 1-by-1 and 2-by-2 diagonal blocks.
subroutineuses a delay and accumulate procedure for performing the off-diagonal updates.
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Notice revision #20110804
This notice covers the following instruction sets: SSE2, SSE4.2, AVX2, AVX-512.
- (global)CHARACTER*1= 'V': update the matrixqof Schur vectors;= 'N': do not updateq.
- (global)array of sizeINTEGERnselectspecifies the eigenvalues in the selected cluster. To select a real eigenvaluew(j),select(must be set to 1. To select a complex conjugate pair of eigenvaluesj)w(j) andw(j+1), corresponding to a 2-by-2 diagonal block, eitherselect(orj)select(or both must be set to 1; a complex conjugate pair of eigenvalues must be either both included in the cluster or both excluded.j+1)
- (global)INTEGER*6Block parameters:
- maximum number of concurrent computational windows allowed in the algorithm; 0 <para(1)≤min(nprow,npcol) must hold;
- number of eigenvalues in each window; 0 <para(2)<para(3)must hold;
- window size;para(2)<para(3)<mb_t<