ctrsyl-f(3)

ctrsyl.f –

Synopsis

Functions/Subroutines

subroutine ctrsyl (TRANA, TRANB, ISGN, M, N, A, LDA, B, LDB, C, LDC, SCALE, INFO)
CTRSYL

Function/Subroutine Documentation

subroutine ctrsyl (characterTRANA, characterTRANB, integerISGN, integerM, integerN, complex, dimension( lda, * )A, integerLDA, complex, dimension( ldb, * )B, integerLDB, complex, dimension( ldc, * )C, integerLDC, realSCALE, integerINFO)

CTRSYL

Purpose:

 CTRSYL 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.

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 is INTEGER
 The order of the matrix A, and the number of rows in the
 matrices X and C. M >= 0.

 N is INTEGER
 The order of the matrix B, and the number of columns in the
 matrices X and C. N >= 0.

 A is COMPLEX 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 is COMPLEX 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 is COMPLEX 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 REAL
 The scale factor, scale, set <= 1 to avoid overflow in X.

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).

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 157 of file ctrsyl.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.