SLATEC Routines --- DBVPOR ---

*DECK DBVPOR
      SUBROUTINE DBVPOR (Y, NROWY, NCOMP, XPTS, NXPTS, A, NROWA, ALPHA,
     +   NIC, B, NROWB, BETA, NFC, IFLAG, Z, MXNON, P, NTP, IP, W, NIV,
     +   YHP, U, V, COEF, S, STOWA, G, WORK, IWORK, NFCC)
C***BEGIN PROLOGUE  DBVPOR
C***SUBSIDIARY
C***PURPOSE  Subsidiary to DBVSUP
C***LIBRARY   SLATEC
C***TYPE      DOUBLE PRECISION (BVPOR-S, DBVPOR-D)
C***AUTHOR  Watts, H. A., (SNLA)
C***DESCRIPTION
C
C **********************************************************************
C     INPUT to DBVPOR    (items not defined in DBVSUP comments)
C **********************************************************************
C
C     NOPG = 0 -- orthonormalization points not pre-assigned
C          = 1 -- orthonormalization points pre-assigned
C
C     MXNON = maximum number of orthogonalizations allowed.
C
C     NDISK = 0 -- in-core storage
C           = 1 -- disk storage.  Value of NTAPE in data statement
C                  is set to 13.  If another value is desired,
C                  the data statement must be changed.
C
C     INTEG = type of integrator and associated test to be used
C             to determine when to orthonormalize.
C
C             1 -- use GRAM-SCHMIDT test and DDERKF
C             2 -- use GRAM-SCHMIDT test and DDEABM
C
C     TOL = tolerance for allowable error in orthogonalization test.
C
C     NPS = 0 normalize particular solution to unit length at each
C             point of orthonormalization.
C         = 1 do not normalize particular solution.
C
C     NTP = must be .GE. NFC*(NFC+1)/2.
C
C     NFCC = 2*NFC for special treatment of a COMPLEX*16 valued problem
C
C     ICOCO = 0 skip final computations (superposition coefficients
C               and, hence, boundary problem solution)
C           = 1 calculate superposition coefficients and obtain
C               solution to the boundary value problem
C
C **********************************************************************
C     OUTPUT from DBVPOR
C **********************************************************************
C
C     Y(NROWY,NXPTS) = solution at specified output points.
C
C     MXNON = number of orthonormalizations performed by DBVPOR.
C
C     Z(MXNON+1) = locations of orthonormalizations performed by DBVPOR.
C
C     NIV = number of independent vectors returned from DMGSBV. Normally
C           this parameter will be meaningful only when DMGSBV returns
C           with MFLAG = 2.
C
C **********************************************************************
C
C     The following variables are in the argument list because of
C     variable dimensioning.  In general, they contain no information of
C     use to the user.  The amount of storage set aside by the user must
C     be greater than or equal to that indicated by the dimension
C     statements.  For the disk storage mode, NON = 0 and KPTS = 1,
C     while for the in-core storage mode, NON = MXNON and KPTS = NXPTS.
C
C     P(NTP,NON+1)
C     IP(NFCC,NON+1)
C     YHP(NCOMP,NFC+1)  plus an additional column of the length  NEQIVP
C     U(NCOMP,NFC,KPTS)
C     V(NCOMP,KPTS)
C     W(NFCC,NON+1)
C     COEF(NFCC)
C     S(NFC+1)
C     STOWA(NCOMP*(NFC+1)+NEQIVP+1)
C     G(NCOMP)
C     WORK(KKKWS)
C     IWORK(LLLIWS)
C
C **********************************************************************
C     SUBROUTINES used by DBVPOR
C         DLSSUD -- solves an underdetermined system of linear
C                   equations.  This routine is used to get a full
C                   set of initial conditions for integration.
C                   Called by DBVPOR.
C
C         DVECS -- obtains starting vectors for special treatment
C                   of COMPLEX*16 valued problems, called by DBVPOR.
C
C         DRKFAB -- routine which conducts integration using DDERKF or
C                   DDEABM.
C
C         DSTWAY -- storage for backup capability, called by
C                   DBVPOR and DREORT.
C
C         DSTOR1 -- storage at output points, called by DBVPOR,
C                   DRKFAB, DREORT and DSTWAY.
C
C         DDOT -- single precision vector inner product routine,
C                   called by DBVPOR, DCOEF, DLSSUD, DMGSBV,
C                   DBKSOL, DREORT and DPRVEC.
C         ** NOTE **
C         a considerable improvement in speed can be achieved if a
C         machine language version is used for DDOT.
C
C         DCOEF -- computes the superposition constants from the
C                   boundary conditions at XFINAL.
C
C         DBKSOL -- solves an upper triangular set of linear equations.
C
C **********************************************************************
C
C***SEE ALSO  DBVSUP
C***ROUTINES CALLED  DBKSOL, DCOEF, DDOT, DLSSUD, DRKFAB, DSTOR1,
C                    DSTWAY, DVECS
C***COMMON BLOCKS    DML15T, DML18J, DML8SZ
C***REVISION HISTORY  (YYMMDD)
C   750601  DATE WRITTEN
C   890531  Changed all specific intrinsics to generic.  (WRB)
C   890831  Modified array declarations.  (WRB)
C   890921  Realigned order of variables in certain COMMON blocks.
C           (WRB)
C   891214  Prologue converted to Version 4.0 format.  (BAB)
C   900328  Added TYPE section.  (WRB)
C   910722  Updated AUTHOR section.  (ALS)
C***END PROLOGUE  DBVPOR