SLATEC Routines --- DBNSLV ---

```*DECK DBNSLV
SUBROUTINE DBNSLV (W, NROWW, NROW, NBANDL, NBANDU, B)
C***BEGIN PROLOGUE  DBNSLV
C***SUBSIDIARY
C***PURPOSE  Subsidiary to DBINT4 and DBINTK
C***LIBRARY   SLATEC
C***TYPE      DOUBLE PRECISION (BNSLV-S, DBNSLV-D)
C***AUTHOR  (UNKNOWN)
C***DESCRIPTION
C
C  DBNSLV is the BANSLV routine from
C        * A Practical Guide to Splines *  by C. de Boor
C
C  DBNSLV is a double precision routine
C
C  Companion routine to  DBNFAC . It returns the solution  X  of the
C  linear system  A*X = B  in place of  B , given the LU-factorization
C  for  A  in the work array  W from DBNFAC.
C
C *****  I N P U T  ****** W,B are DOUBLE PRECISION
C  W, NROWW,NROW,NBANDL,NBANDU.....Describe the LU-factorization of a
C        banded matrix  A  of order  NROW  as constructed in  DBNFAC .
C        For details, see  DBNFAC .
C  B.....Right side of the system to be solved .
C
C *****  O U T P U T  ****** B is DOUBLE PRECISION
C  B.....Contains the solution  X , of order  NROW .
C
C *****  M E T H O D  ******
C     (With  A = L*U, as stored in  W,) the unit lower triangular system
C  L(U*X) = B  is solved for  Y = U*X, and  Y  stored in  B . Then the
C  upper triangular system  U*X = Y  is solved for  X  . The calcul-
C  ations are so arranged that the innermost loops stay within columns.
C