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- *DECK DFSPVN
- SUBROUTINE DFSPVN (T, JHIGH, INDEX, X, ILEFT, VNIKX)
- C***BEGIN PROLOGUE DFSPVN
- C***SUBSIDIARY
- C***PURPOSE Subsidiary to DFC
- C***LIBRARY SLATEC
- C***TYPE DOUBLE PRECISION (BSPLVN-S, DFSPVN-D)
- C***AUTHOR (UNKNOWN)
- C***DESCRIPTION
- C
- C **** Double Precision version of BSPLVN ****
- C
- C Calculates the value of all possibly nonzero B-splines at *X* of
- C order MAX(JHIGH,(J+1)(INDEX-1)) on *T*.
- C
- C***SEE ALSO DFC
- C***ROUTINES CALLED (NONE)
- C***REVISION HISTORY (YYMMDD)
- C 780801 DATE WRITTEN
- C 891214 Prologue converted to Version 4.0 format. (BAB)
- C 900328 Added TYPE section. (WRB)
- C***END PROLOGUE DFSPVN
- IMPLICIT DOUBLE PRECISION (A-H,O-Z)
- DIMENSION T(*),VNIKX(*)
- DIMENSION DELTAM(20),DELTAP(20)
- SAVE J, DELTAM, DELTAP
- DATA J/1/,(DELTAM(I),I=1,20),(DELTAP(I),I=1,20)/40*0.0D0/
- C***FIRST EXECUTABLE STATEMENT DFSPVN
- GO TO (10,20),INDEX
- 10 J = 1
- VNIKX(1) = 1.D0
- IF (J .GE. JHIGH) GO TO 99
- C
- 20 IPJ = ILEFT+J
- DELTAP(J) = T(IPJ) - X
- IMJP1 = ILEFT-J+1
- DELTAM(J) = X - T(IMJP1)
- VMPREV = 0.D0
- JP1 = J+1
- DO 26 L=1,J
- JP1ML = JP1-L
- VM = VNIKX(L)/(DELTAP(L) + DELTAM(JP1ML))
- VNIKX(L) = VM*DELTAP(L) + VMPREV
- 26 VMPREV = VM*DELTAM(JP1ML)
- VNIKX(JP1) = VMPREV
- J = JP1
- IF (J .LT. JHIGH) GO TO 20
- C
- 99 RETURN
- END
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