LAPACK
3.6.1
LAPACK: Linear Algebra PACKage
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subroutine ctgex2 | ( | logical | WANTQ, |
logical | WANTZ, | ||
integer | N, | ||
complex, dimension( lda, * ) | A, | ||
integer | LDA, | ||
complex, dimension( ldb, * ) | B, | ||
integer | LDB, | ||
complex, dimension( ldq, * ) | Q, | ||
integer | LDQ, | ||
complex, dimension( ldz, * ) | Z, | ||
integer | LDZ, | ||
integer | J1, | ||
integer | INFO | ||
) |
CTGEX2 swaps adjacent diagonal blocks in an upper (quasi) triangular matrix pair by an unitary equivalence transformation.
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CTGEX2 swaps adjacent diagonal 1 by 1 blocks (A11,B11) and (A22,B22) in an upper triangular matrix pair (A, B) by an unitary equivalence transformation. (A, B) must be in generalized Schur canonical form, that is, A and B are both upper triangular. Optionally, the matrices Q and Z of generalized Schur vectors are updated. Q(in) * A(in) * Z(in)**H = Q(out) * A(out) * Z(out)**H Q(in) * B(in) * Z(in)**H = Q(out) * B(out) * Z(out)**H
[in] | WANTQ | WANTQ is LOGICAL .TRUE. : update the left transformation matrix Q; .FALSE.: do not update Q. |
[in] | WANTZ | WANTZ is LOGICAL .TRUE. : update the right transformation matrix Z; .FALSE.: do not update Z. |
[in] | N | N is INTEGER The order of the matrices A and B. N >= 0. |
[in,out] | A | A is COMPLEX arrays, dimensions (LDA,N) On entry, the matrix A in the pair (A, B). On exit, the updated matrix A. |
[in] | LDA | LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N). |
[in,out] | B | B is COMPLEX arrays, dimensions (LDB,N) On entry, the matrix B in the pair (A, B). On exit, the updated matrix B. |
[in] | LDB | LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N). |
[in,out] | Q | Q is COMPLEX array, dimension (LDZ,N) If WANTQ = .TRUE, on entry, the unitary matrix Q. On exit, the updated matrix Q. Not referenced if WANTQ = .FALSE.. |
[in] | LDQ | LDQ is INTEGER The leading dimension of the array Q. LDQ >= 1; If WANTQ = .TRUE., LDQ >= N. |
[in,out] | Z | Z is COMPLEX array, dimension (LDZ,N) If WANTZ = .TRUE, on entry, the unitary matrix Z. On exit, the updated matrix Z. Not referenced if WANTZ = .FALSE.. |
[in] | LDZ | LDZ is INTEGER The leading dimension of the array Z. LDZ >= 1; If WANTZ = .TRUE., LDZ >= N. |
[in] | J1 | J1 is INTEGER The index to the first block (A11, B11). |
[out] | INFO | INFO is INTEGER =0: Successful exit. =1: The transformed matrix pair (A, B) would be too far from generalized Schur form; the problem is ill- conditioned. |
Definition at line 192 of file ctgex2.f.