text: *> \brief \b SPBTRS
  *
  *  =========== DOCUMENTATION ===========
  *
  * Online html documentation available at
  *            http://www.netlib.org/lapack/explore-html/
  *
  *> \htmlonly
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  *> [TXT]</a>
  *> \endhtmlonly
  *
  *  Definition:
  *  ===========
  *
  *       SUBROUTINE SPBTRS( UPLO, N, KD, NRHS, AB, LDAB, B, LDB, INFO )
  *
  *       .. Scalar Arguments ..
  *       CHARACTER          UPLO
  *       INTEGER            INFO, KD, LDAB, LDB, N, NRHS
  *       ..
  *       .. Array Arguments ..
  *       REAL               AB( LDAB, * ), B( LDB, * )
  *       ..
  *
  *
  *> \par Purpose:
  *  =============
  *>
  *> \verbatim
  *>
  *> SPBTRS solves a system of linear equations A*X = B with a symmetric
  *> positive definite band matrix A using the Cholesky factorization
  *> A = U**T*U or A = L*L**T computed by SPBTRF.
  *> \endverbatim
  *
  *  Arguments:
  *  ==========
  *
  *> \param[in] UPLO
  *> \verbatim
  *>          UPLO is CHARACTER*1
  *>          = 'U':  Upper triangular factor stored in AB;
  *>          = 'L':  Lower triangular factor stored in AB.
  *> \endverbatim
  *>
  *> \param[in] N
  *> \verbatim
  *>          N is INTEGER
  *>          The order of the matrix A.  N >= 0.
  *> \endverbatim
  *>
  *> \param[in] KD
  *> \verbatim
  *>          KD is INTEGER
  *>          The number of superdiagonals of the matrix A if UPLO = 'U',
  *>          or the number of subdiagonals if UPLO = 'L'.  KD >= 0.
  *> \endverbatim
  *>
  *> \param[in] NRHS
  *> \verbatim
  *>          NRHS is INTEGER
  *>          The number of right hand sides, i.e., the number of columns
  *>          of the matrix B.  NRHS >= 0.
  *> \endverbatim
  *>
  *> \param[in] AB
  *> \verbatim
  *>          AB is REAL array, dimension (LDAB,N)
  *>          The triangular factor U or L from the Cholesky factorization
  *>          A = U**T*U or A = L*L**T of the band matrix A, stored in the
  *>          first KD+1 rows of the array.  The j-th column of U or L is
  *>          stored in the j-th column of the array AB as follows:
  *>          if UPLO ='U', AB(kd+1+i-j,j) = U(i,j) for max(1,j-kd)<=i<=j;
  *>          if UPLO ='L', AB(1+i-j,j)    = L(i,j) for j<=i<=min(n,j+kd).
  *> \endverbatim
  *>
  *> \param[in] LDAB
  *> \verbatim
  *>          LDAB is INTEGER
  *>          The leading dimension of the array AB.  LDAB >= KD+1.
  *> \endverbatim
  *>
  *> \param[in,out] B
  *> \verbatim
  *>          B is REAL array, dimension (LDB,NRHS)
  *>          On entry, the right hand side matrix B.
  *>          On exit, the solution matrix X.
  *> \endverbatim
  *>
  *> \param[in] LDB
  *> \verbatim
  *>          LDB is INTEGER
  *>          The leading dimension of the array B.  LDB >= max(1,N).
  *> \endverbatim
  *>
  *> \param[out] INFO
  *> \verbatim
  *>          INFO is INTEGER
  *>          = 0:  successful exit
  *>          < 0:  if INFO = -i, the i-th argument had an illegal value
  *> \endverbatim
  *
  *  Authors:
  *  ========
  *
  *> \author Univ. of Tennessee
  *> \author Univ. of California Berkeley
  *> \author Univ. of Colorado Denver
  *> \author NAG Ltd.
  *
  *> \date December 2016
  *
  *> \ingroup realOTHERcomputational
  *
  *  =====================================================================
        SUBROUTINE SPBTRS( UPLO, N, KD, NRHS, AB, LDAB, B, LDB, INFO )
  *
  *  -- LAPACK computational routine (version 3.7.0) --
  *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
  *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
  *     December 2016
  *
  *     .. Scalar Arguments ..
        CHARACTER          UPLO
        INTEGER            INFO, KD, LDAB, LDB, N, NRHS
  *     ..
  *     .. Array Arguments ..
        REAL               AB( LDAB, * ), B( LDB, * )
  *     ..
  *
  *  =====================================================================
  *
  *     .. Local Scalars ..
        LOGICAL            UPPER
        INTEGER            J
  *     ..
  *     .. External Functions ..
        LOGICAL            LSAME
        EXTERNAL           LSAME
  *     ..
  *     .. External Subroutines ..
        EXTERNAL           STBSV, XERBLA
  *     ..
  *     .. Intrinsic Functions ..
        INTRINSIC          MAX
  *     ..
  *     .. Executable Statements ..
  *
  *     Test the input parameters.
  *
        INFO = 0
        UPPER = LSAME( UPLO, 'U' )
        IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
           INFO = -1
        ELSE IF( N.LT.0 ) THEN
           INFO = -2
        ELSE IF( KD.LT.0 ) THEN
           INFO = -3
        ELSE IF( NRHS.LT.0 ) THEN
           INFO = -4
        ELSE IF( LDAB.LT.KD+1 ) THEN
           INFO = -6
        ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
           INFO = -8
        END IF
        IF( INFO.NE.0 ) THEN
           CALL XERBLA( 'SPBTRS', -INFO )
           RETURN
        END IF
  *
  *     Quick return if possible
  *
        IF( N.EQ.0 .OR. NRHS.EQ.0 )
       $   RETURN
  *
        IF( UPPER ) THEN
  *
  *        Solve A*X = B where A = U**T *U.
  *
           DO 10 J = 1, NRHS
  *
  *           Solve U**T *X = B, overwriting B with X.
  *
              CALL STBSV( 'Upper', 'Transpose', 'Non-unit', N, KD, AB,
       $                  LDAB, B( 1, J ), 1 )
  *
  *           Solve U*X = B, overwriting B with X.
  *
              CALL STBSV( 'Upper', 'No transpose', 'Non-unit', N, KD, AB,
       $                  LDAB, B( 1, J ), 1 )
     10    CONTINUE
        ELSE
  *
  *        Solve A*X = B where A = L*L**T.
  *
           DO 20 J = 1, NRHS
  *
  *           Solve L*X = B, overwriting B with X.
  *
              CALL STBSV( 'Lower', 'No transpose', 'Non-unit', N, KD, AB,
       $                  LDAB, B( 1, J ), 1 )
  *
  *           Solve L**T *X = B, overwriting B with X.
  *
              CALL STBSV( 'Lower', 'Transpose', 'Non-unit', N, KD, AB,
       $                  LDAB, B( 1, J ), 1 )
     20    CONTINUE
        END IF
  *
        RETURN
  *
  *     End of SPBTRS
  *
        END
  