SRC/ztrsyl3.f(3) | Library Functions Manual | SRC/ztrsyl3.f(3) |
NAME
SRC/ztrsyl3.f
SYNOPSIS
Functions/Subroutines
subroutine ztrsyl3 (trana, tranb, isgn, m, n, a, lda, b,
ldb, c, ldc, scale, swork, ldswork, info)
ZTRSYL3
Function/Subroutine Documentation
subroutine ztrsyl3 (character trana, character tranb, integer isgn, integer m, integer n, complex*16, dimension( lda, * ) a, integer lda, complex*16, dimension( ldb, * ) b, integer ldb, complex*16, dimension( ldc, * ) c, integer ldc, double precision scale, double precision, dimension( ldswork, * ) swork, integer ldswork, integer info)
ZTRSYL3
Purpose
ZTRSYL3 solves the complex 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**H, and A and B are both upper 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. This is the block version of the algorithm.
Parameters
TRANA
TRANA is CHARACTER*1 Specifies the option op(A): = 'N': op(A) = A (No transpose) = 'C': op(A) = A**H (Conjugate transpose)
TRANB
TRANB is CHARACTER*1 Specifies the option op(B): = 'N': op(B) = B (No transpose) = 'C': op(B) = B**H (Conjugate transpose)
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
M
M is INTEGER The order of the matrix A, and the number of rows in the matrices X and C. M >= 0.
N
N is INTEGER The order of the matrix B, and the number of columns in the matrices X and C. N >= 0.
A
A is COMPLEX*16 array, dimension (LDA,M) The upper triangular matrix A.
LDA
LDA is INTEGER The leading dimension of the array A. LDA >= max(1,M).
B
B is COMPLEX*16 array, dimension (LDB,N) The upper triangular matrix B.
LDB
LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N).
C
C is COMPLEX*16 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.
LDC
LDC is INTEGER The leading dimension of the array C. LDC >= max(1,M)
SCALE
SCALE is DOUBLE PRECISION The scale factor, scale, set <= 1 to avoid overflow in X.
SWORK
SWORK is DOUBLE PRECISION array, dimension (MAX(2, ROWS), MAX(1,COLS)). On exit, if INFO = 0, SWORK(1) returns the optimal value ROWS and SWORK(2) returns the optimal COLS.
LDSWORK
LDSWORK is INTEGER LDSWORK >= MAX(2,ROWS), where ROWS = ((M + NB - 1) / NB + 1) and NB is the optimal block size. If LDSWORK = -1, then a workspace query is assumed; the routine only calculates the optimal dimensions of the SWORK matrix, returns these values as the first and second entry of the SWORK matrix, and no error message related LWORK is issued by XERBLA.
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).
Definition at line 155 of file ztrsyl3.f.
Author
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