dbnslv.f
SUBROUTINE DBNSLV (W, NROWW, NROW, NBANDL, NBANDU, B)
C***BEGIN PROLOGUE DBNSLV
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Warning: this routine is not intended to be user-callable.
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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
C***SEE ALSO DBINT4, DBINTK
C***ROUTINES CALLED (NONE)
C***REVISION HISTORY (YYMMDD)
C 800901 DATE WRITTEN
C 890531 Changed all specific intrinsics to generic. (WRB)
C 890831 Modified array declarations. (WRB)
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 900328 Added TYPE section. (WRB)
C***END PROLOGUE DBNSLV