ppqad.f
SUBROUTINE PPQAD (LDC, C, XI, LXI, K, X1, X2, PQUAD)
C***BEGIN PROLOGUE PPQAD
C***PURPOSE Compute the integral on (X1,X2) of a K-th order B-spline
C using the piecewise polynomial (PP) representation.
C***LIBRARY SLATEC
C***CATEGORY H2A2A1, E3, K6
C***TYPE SINGLE PRECISION (PPQAD-S, DPPQAD-D)
C***KEYWORDS B-SPLINE, DATA FITTING, INTERPOLATION, QUADRATURE, SPLINES
C***AUTHOR Amos, D. E., (SNLA)
C***DESCRIPTION
C
C Abstract
C PPQAD computes the integral on (X1,X2) of a K-th order
C B-spline using the piecewise polynomial representation
C (C,XI,LXI,K). Here the Taylor expansion about the left
C end point XI(J) of the J-th interval is integrated and
C evaluated on subintervals of (X1,X2) which are formed by
C included break points. Integration outside (XI(1),XI(LXI+1))
C is permitted.
C
C Description of Arguments
C Input
C LDC - leading dimension of matrix C, LDC .GE. K
C C(I,J) - right Taylor derivatives at XI(J), I=1,K , J=1,LXI
C XI(*) - break point array of length LXI+1
C LXI - number of polynomial pieces
C K - order of B-spline, K .GE. 1
C X1,X2 - end points of quadrature interval, normally in
C XI(1) .LE. X .LE. XI(LXI+1)
C
C Output
C PQUAD - integral of the PP representation over (X1,X2)
C
C Error Conditions
C Improper input is a fatal error
C
C***REFERENCES D. E. Amos, Quadrature subroutines for splines and
C B-splines, Report SAND79-1825, Sandia Laboratories,
C December 1979.
C***ROUTINES CALLED INTRV, XERMSG
C***REVISION HISTORY (YYMMDD)
C 800901 DATE WRITTEN
C 890531 Changed all specific intrinsics to generic. (WRB)
C 890531 REVISION DATE from Version 3.2
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 900315 CALLs to XERROR changed to CALLs to XERMSG. (THJ)
C 920501 Reformatted the REFERENCES section. (WRB)
C***END PROLOGUE PPQAD