DBNSLV(3)

SYNOPSIS
SUBROUTINE DBNSLV (W, NROWW, NROW, NBANDL, NBANDU, B)

NAME
dbnslv - Subsidiary to DBINT4 and DBINTK

LIBRARY
SLATEC

TYPE
DOUBLE PRECISION (BNSLV-S, DBNSLV-D)

AUTHOR
(UNKNOWN)

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

SEE ALSO
DBINT4, DBINTK

ROUTINES CALLED
(NONE)

REVISION HISTORY (YYMMDD)
800901 DATE WRITTEN
890531 Changed all specific intrinsics to generic. (WRB)
890831 Modified array declarations. (WRB)
891214 Prologue converted to Version 4.0 format. (BAB)
900328 Added TYPE section. (WRB)