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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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| subroutine strsyl | ( | character | TRANA, |
| character | TRANB, | ||
| integer | ISGN, | ||
| integer | M, | ||
| integer | N, | ||
| real, dimension( lda, * ) | A, | ||
| integer | LDA, | ||
| real, dimension( ldb, * ) | B, | ||
| integer | LDB, | ||
| real, dimension( ldc, * ) | C, | ||
| integer | LDC, | ||
| real | SCALE, | ||
| integer | INFO | ||
| ) |
STRSYL
Download STRSYL + dependencies [TGZ] [ZIP] [TXT]
STRSYL solves the real Sylvester matrix equation:
op(A)*X + X*op(B) = scale*C or
op(A)*X - X*op(B) = scale*C,
where op(A) = A or A**T, and A and B are both upper quasi-
triangular. A is M-by-M and B is N-by-N; the right hand side C and
the solution X are M-by-N; and scale is an output scale factor, set
<= 1 to avoid overflow in X.
A and B must be in Schur canonical form (as returned by SHSEQR), that
is, block upper triangular with 1-by-1 and 2-by-2 diagonal blocks;
each 2-by-2 diagonal block has its diagonal elements equal and its
off-diagonal elements of opposite sign. | [in] | TRANA | TRANA is CHARACTER*1
Specifies the option op(A):
= 'N': op(A) = A (No transpose)
= 'T': op(A) = A**T (Transpose)
= 'C': op(A) = A**H (Conjugate transpose = Transpose) |
| [in] | TRANB | TRANB is CHARACTER*1
Specifies the option op(B):
= 'N': op(B) = B (No transpose)
= 'T': op(B) = B**T (Transpose)
= 'C': op(B) = B**H (Conjugate transpose = Transpose) |
| [in] | ISGN | ISGN is INTEGER
Specifies the sign in the equation:
= +1: solve op(A)*X + X*op(B) = scale*C
= -1: solve op(A)*X - X*op(B) = scale*C |
| [in] | M | M is INTEGER
The order of the matrix A, and the number of rows in the
matrices X and C. M >= 0. |
| [in] | N | N is INTEGER
The order of the matrix B, and the number of columns in the
matrices X and C. N >= 0. |
| [in] | A | A is REAL array, dimension (LDA,M)
The upper quasi-triangular matrix A, in Schur canonical form. |
| [in] | LDA | LDA is INTEGER
The leading dimension of the array A. LDA >= max(1,M). |
| [in] | B | B is REAL array, dimension (LDB,N)
The upper quasi-triangular matrix B, in Schur canonical form. |
| [in] | LDB | LDB is INTEGER
The leading dimension of the array B. LDB >= max(1,N). |
| [in,out] | C | C is REAL array, dimension (LDC,N)
On entry, the M-by-N right hand side matrix C.
On exit, C is overwritten by the solution matrix X. |
| [in] | LDC | LDC is INTEGER
The leading dimension of the array C. LDC >= max(1,M) |
| [out] | SCALE | SCALE is REAL
The scale factor, scale, set <= 1 to avoid overflow in X. |
| [out] | INFO | INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
= 1: A and B have common or very close eigenvalues; perturbed
values were used to solve the equation (but the matrices
A and B are unchanged). |
1.9.4