# SLATEC Routines --- DBSGQ8 ---

```*DECK DBSGQ8
SUBROUTINE DBSGQ8 (FUN, XT, BC, N, KK, ID, A, B, INBV, ERR, ANS,
+   IERR, WORK)
C***BEGIN PROLOGUE  DBSGQ8
C***SUBSIDIARY
C***LIBRARY   SLATEC
C***TYPE      DOUBLE PRECISION (BSGQ8-S, DBSGQ8-D)
C***AUTHOR  Jones, R. E., (SNLA)
C***DESCRIPTION
C
C     Abstract    **** A DOUBLE PRECISION routine ****
C
C        DBSGQ8, a modification of GAUS8, integrates the
C        product of FUN(X) by the ID-th derivative of a spline
C        DBVALU(XT,BC,N,KK,ID,X,INBV,WORK)  between limits A and B.
C
C     Description of Arguments
C
C        INPUT-- FUN,XT,BC,A,B,ERR are DOUBLE PRECISION
C        FUN - Name of external function of one argument which
C              multiplies DBVALU.
C        XT  - Knot array for DBVALU
C        BC  - B-coefficient array for DBVALU
C        N   - Number of B-coefficients for DBVALU
C        KK  - Order of the spline, KK.GE.1
C        ID  - Order of the spline derivative, 0.LE.ID.LE.KK-1
C        A   - Lower limit of integral
C        B   - Upper limit of integral (may be less than A)
C        INBV- Initialization parameter for DBVALU
C        ERR - Is a requested pseudorelative error tolerance.  Normally
C              pick a value of ABS(ERR).LT.1D-3.  ANS will normally
C              have no more error than ABS(ERR) times the integral of
C              the absolute value of FUN(X)*DBVALU(XT,BC,N,KK,X,ID,
C              INBV,WORK).
C
C
C        OUTPUT-- ERR,ANS,WORK are DOUBLE PRECISION
C        ERR - Will be an estimate of the absolute error in ANS if the
C              input value of ERR was negative.  (ERR is unchanged if
C              the input value of ERR was nonnegative.)  The estimated
C              error is solely for information to the user and should
C              not be used as a correction to the computed integral.
C        ANS - Computed value of integral
C        IERR- A status code
C            --Normal Codes
C               1 ANS most likely meets requested error tolerance,
C                 or A=B.
C              -1 A and B are too nearly equal to allow normal
C                 integration.  ANS is set to zero.
C            --Abnormal Code
C               2 ANS probably does not meet requested error tolerance.
C        WORK- Work vector of length 3*K for DBVALU
C