.TH "strsyl.f" 3 "Wed Oct 15 2014" "Version 3.4.2" "LAPACK" \" -*- nroff -*- .ad l .nh .SH NAME strsyl.f \- .SH SYNOPSIS .br .PP .SS "Functions/Subroutines" .in +1c .ti -1c .RI "subroutine \fBstrsyl\fP (TRANA, TRANB, ISGN, M, N, A, LDA, B, LDB, C, LDC, SCALE, INFO)" .br .RI "\fI\fBSTRSYL\fP \fP" .in -1c .SH "Function/Subroutine Documentation" .PP .SS "subroutine strsyl (characterTRANA, characterTRANB, integerISGN, integerM, integerN, real, dimension( lda, * )A, integerLDA, real, dimension( ldb, * )B, integerLDB, real, dimension( ldc, * )C, integerLDC, realSCALE, integerINFO)" .PP \fBSTRSYL\fP .PP \fBPurpose: \fP .RS 4 .PP .nf 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. .fi .PP .RE .PP \fBParameters:\fP .RS 4 \fITRANA\fP .PP .nf 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) .fi .PP .br \fITRANB\fP .PP .nf 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) .fi .PP .br \fIISGN\fP .PP .nf 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 .fi .PP .br \fIM\fP .PP .nf M is INTEGER The order of the matrix A, and the number of rows in the matrices X and C. M >= 0. .fi .PP .br \fIN\fP .PP .nf N is INTEGER The order of the matrix B, and the number of columns in the matrices X and C. N >= 0. .fi .PP .br \fIA\fP .PP .nf A is REAL array, dimension (LDA,M) The upper quasi-triangular matrix A, in Schur canonical form. .fi .PP .br \fILDA\fP .PP .nf LDA is INTEGER The leading dimension of the array A. LDA >= max(1,M). .fi .PP .br \fIB\fP .PP .nf B is REAL array, dimension (LDB,N) The upper quasi-triangular matrix B, in Schur canonical form. .fi .PP .br \fILDB\fP .PP .nf LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N). .fi .PP .br \fIC\fP .PP .nf 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. .fi .PP .br \fILDC\fP .PP .nf LDC is INTEGER The leading dimension of the array C. LDC >= max(1,M) .fi .PP .br \fISCALE\fP .PP .nf SCALE is REAL The scale factor, scale, set <= 1 to avoid overflow in X. .fi .PP .br \fIINFO\fP .PP .nf 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). .fi .PP .RE .PP \fBAuthor:\fP .RS 4 Univ\&. of Tennessee .PP Univ\&. of California Berkeley .PP Univ\&. of Colorado Denver .PP NAG Ltd\&. .RE .PP \fBDate:\fP .RS 4 November 2011 .RE .PP .PP Definition at line 164 of file strsyl\&.f\&. .SH "Author" .PP Generated automatically by Doxygen for LAPACK from the source code\&.