SLASORTE(l) | LAPACK routine (version 1.5) | SLASORTE(l) |
NAME¶
SLASORTE - sort eigenpairs so that real eigenpairs are together and complex are togetherSYNOPSIS¶
- SUBROUTINE SLASORTE
- ( S, LDS, J, OUT, INFO )
PURPOSE¶
SLASORTE sorts eigenpairs so that real eigenpairs are together andcomplex are together. This way one can employ 2x2 shifts easily
since every 2nd subdiagonal is guaranteed to be zero.
ARGUMENTS¶
- S (local input/output) REAL array, dimension LDS
- On entry, a matrix already in Schur form. On exit, the diagonal blocks of S have been rewritten to pair the eigenvalues. The resulting matrix is no longer similar to the input.
- LDS (local input) INTEGER
- On entry, the leading dimension of the local array S. Unchanged on exit.
- J (local input) INTEGER
- On entry, the order of the matrix S. Unchanged on exit.
- OUT (local input/output) REAL array, dimension Jx2
- This is the work buffer required by this routine.
- INFO (local input) INTEGER
- This is set if the input matrix had an odd number of real eigenvalues and things couldn't be paired or if the input matrix S was not originally in Schur form. 0 indicates successful completion. Implemented by: G. Henry, May 1, 1997
12 May 1997 | LAPACK version 1.5 |