solve

CTRSYL(l)								 )								 CTRSYL(l)

NAME

       CTRSYL - solve the complex Sylvester matrix equation

SYNOPSIS

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

	   CHARACTER	  TRANA, TRANB

	   INTEGER	  INFO, ISGN, LDA, LDB, LDC, M, N

	   REAL 	  SCALE

	   COMPLEX	  A( LDA, * ), B( LDB, * ), C( LDC, * )

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.

ARGUMENTS

       TRANA   (input) CHARACTER*1
	       Specifies the option op(A):
	       = 'N': op(A) = A    (No transpose)
	       = 'C': op(A) = A**H (Conjugate transpose)

       TRANB   (input) CHARACTER*1
	       Specifies the option op(B):
	       = 'N': op(B) = B    (No transpose)
	       = 'C': op(B) = B**H (Conjugate transpose)

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

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

       A       (input) COMPLEX array, dimension (LDA,M)
	       The upper triangular matrix A.

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

       B       (input) COMPLEX array, dimension (LDB,N)
	       The upper triangular matrix B.

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

       C       (input/output) 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     (input) INTEGER
	       The leading dimension of the array C. LDC >= max(1,M)

       SCALE   (output) REAL
	       The scale factor, scale, set <= 1 to avoid overflow in X.

       INFO    (output) 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).

LAPACK version 3.0						   15 June 2000 							 CTRSYL(l)