dtrsyl.f(3)							      LAPACK							       dtrsyl.f(3)

NAME

       dtrsyl.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dtrsyl (TRANA, TRANB, ISGN, M, N, A, LDA, B, LDB, C, LDC, SCALE, INFO)
	   DTRSYL

Function/Subroutine Documentation
   subroutine dtrsyl (characterTRANA, characterTRANB, integerISGN, integerM, integerN, double precision, dimension( lda, * )A, integerLDA, double
       precision, dimension( ldb, * )B, integerLDB, double precision, dimension( ldc, * )C, integerLDC, double precisionSCALE, integerINFO)
       DTRSYL

       Purpose:

	    DTRSYL 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 DHSEQR), 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.

       Parameters:
	   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)

	   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)

	   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 DOUBLE PRECISION array, dimension (LDA,M)
		     The upper quasi-triangular matrix A, in Schur canonical form.

	   LDA

		     LDA is INTEGER
		     The leading dimension of the array A. LDA >= max(1,M).

	   B

		     B is DOUBLE PRECISION array, dimension (LDB,N)
		     The upper quasi-triangular matrix B, in Schur canonical form.

	   LDB

		     LDB is INTEGER
		     The leading dimension of the array B. LDB >= max(1,N).

	   C

		     C is DOUBLE PRECISION 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.

	   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 164 of file dtrsyl.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2							  Tue Sep 25 2012						       dtrsyl.f(3)