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IMSL Name:  BS3VL/DBS3VL (Single/Double precision version)
 
Revised:    June 10, 1991
 
Purpose:    Evaluate a three-dimensional tensor-product spline,
            given its tensor-product B-spline representation.
 
Usage:      BS3VL(X, Y, Z, KXORD, KYORD, KZORD, XKNOT, YKNOT, ZKNOT,
                  NXCOEF, NYCOEF, NZCOEF, BSCOEF)
 
Arguments:
   X      - X-coordinate of the point at which the spline is to be
            evaluated.  (Input)
   Y      - Y-coordinate of the point at which the spline is to be
            evaluated.  (Input)
   Z      - Z-coordinate of the point at which the spline is to be
            evaluated.  (Input)
   KXORD  - Order of the spline in the X-direction.  (Input)
   KYORD  - Order of the spline in the Y-direction.  (Input)
   KZORD  - Order of the spline in the Z-direction.  (Input)
   XKNOT  - Array of length NXCOEF+KXORD containing the knot
            sequence in the X-direction.  (Input)
            XKNOT must be nondecreasing.
   YKNOT  - Array of length NYCOEF+KYORD containing the knot
            sequence in the Y-direction.  (Input)
            YKNOT must be nondecreasing.
   ZKNOT  - Array of length NZCOEF+KZORD containing the knot
            sequence in the Z-direction.  (Input)
            ZKNOT must be nondecreasing.
   NXCOEF - Number of B-spline coefficients in the X-direction.
            (Input)
   NYCOEF - Number of B-spline coefficients in the Y-direction.
            (Input)
   NZCOEF - Number of B-spline coefficients in the Z-direction.
            (Input)
   BSCOEF - Array of length NXCOEF*NYCOEF*NZCOEF containing the
            tensor-product B-spline coefficients.  (Input)
            BSCOEF is treated internally as a matrix of size NXCOEF
            by NYCOEF by NZCOEF.
   BS3VL  - Value of the spline at (X,Y,Z).  (Output)
 
Remark:
   Automatic workspace usage is
            BS3VL    3*MAX(KXORD,KYORD,KZORD)+KYORD*KZORD+KZORD
                     units, or
            DBS3VL   6*MAX(KXORD,KYORD,KZORD)+2*KYORD*KZORD+2*KZORD
                     units.
   Workspace may be explicitly provided, if desired, by use of
   B23VL/DB23VL.  The reference is
            CALL B23VL(X, Y, Z, KXORD, KYORD, KZORD, XKNOT, YKNOT,
                       ZKNOT, NXCOEF, NYCOEF, NZCOEF, BSCOEF, WK)
   The additional argument is
   WK     - Work array of length
            3*MAX(KXORD,KYORD,KZORD)+KYORD*KZORD +KZORD.
 
GAMS:       E3a1
 
Chapter:    MATH/LIBRARY Interpolation and Approximation
 
Page No.:   MATH/LIBRARY User's Manual page 572