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DTBTRS(l)			       )			     DTBTRS(l)

NAME
       DTBTRS - solve a triangular system of the form  A * X = B or A**T * X =
       B,

SYNOPSIS
       SUBROUTINE DTBTRS( UPLO, TRANS, DIAG, N, KD, NRHS, AB,  LDAB,  B,  LDB,
			  INFO )

	   CHARACTER	  DIAG, TRANS, UPLO

	   INTEGER	  INFO, KD, LDAB, LDB, N, NRHS

	   DOUBLE	  PRECISION AB( LDAB, * ), B( LDB, * )

PURPOSE
       DTBTRS  solves  a triangular system of the form A * X = B or A**T * X =
       B, where A is a triangular band matrix of order N, and  B  is  an  N-by
       NRHS matrix.  A check is made to verify that A is nonsingular.

ARGUMENTS
       UPLO    (input) CHARACTER*1
	       = 'U':  A is upper triangular;
	       = 'L':  A is lower triangular.

       TRANS   (input) CHARACTER*1
	       Specifies the form the system of equations:
	       = 'N':  A * X = B  (No transpose)
	       = 'T':  A**T * X = B  (Transpose)
	       = 'C':  A**H * X = B  (Conjugate transpose = Transpose)

       DIAG    (input) CHARACTER*1
	       = 'N':  A is non-unit triangular;
	       = 'U':  A is unit triangular.

       N       (input) INTEGER
	       The order of the matrix A.  N >= 0.

       KD      (input) INTEGER
	       The  number of superdiagonals or subdiagonals of the triangular
	       band matrix A.  KD >= 0.

       NRHS    (input) INTEGER
	       The number of right hand sides, i.e., the number of columns  of
	       the matrix B.  NRHS >= 0.

       AB      (input) DOUBLE PRECISION array, dimension (LDAB,N)
	       The  upper  or  lower  triangular  band matrix A, stored in the
	       first kd+1 rows of AB.  The j-th column of A is stored  in  the
	       j-th  column  of	 the  array  AB	 as  follows:  if  UPLO = 'U',
	       AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j; if UPLO  =  'L',
	       AB(1+i-j,j)     = A(i,j) for j<=i<=min(n,j+kd).	If DIAG = 'U',
	       the diagonal elements of A are not referenced and  are  assumed
	       to be 1.

       LDAB    (input) INTEGER
	       The leading dimension of the array AB.  LDAB >= KD+1.

       B       (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
	       On  entry, the right hand side matrix B.	 On exit, if INFO = 0,
	       the solution matrix X.

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

       INFO    (output) INTEGER
	       = 0:  successful exit
	       < 0:  if INFO = -i, the i-th argument had an illegal value
	       > 0:  if INFO = i, the i-th diagonal  element  of  A  is	 zero,
	       indicating that the matrix is singular and the solutions X have
	       not been computed.

LAPACK version 3.0		 15 June 2000			     DTBTRS(l)
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