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IMSL Name:  BSDER/DBSDER (Single/Double precision version)
 
Revised:    June 10, 1991
 
Purpose:    Evaluate the derivative of a spline, given its B-spline
            representation.
 
Usage:      BSDER(IDERIV, X, KORDER, XKNOT, NCOEF, BSCOEF)
 
Arguments:
   IDERIV - Order of the derivative to be evaluated.  (Input)
            In particular, IDERIV = 0 returns the value of the
            spline.
   X      - Point at which the spline is to be evaluated.  (Input)
   KORDER - Order of the spline.  (Input)
   XKNOT  - Array of length NCOEF+KORDER containing the knot
            sequence.  (Input)
            XKNOT must be nondecreasing.
   NCOEF  - Number of B-spline coefficients.  (Input)
   BSCOEF - Array of length NCOEF containing the B-spline
            coefficients.  (Input)
   BSDER  - Value of the IDERIV-th derivative of the spline at X.
            (Output)
 
Remarks:
1. Automatic workspace usage is
            BSDER    3*KORDER units, or
            DBSDER   6*KORDER units.
   Workspace may be explicitly provided, if desired, by use of
   B2DER/DB2DER.  The reference is
            CALL B2DER(IDERIV, X, KORDER, XKNOT, NCOEF, BSCOEF, WK1,
                       WK2, WK3)
   The additional arguments are as follows:
   WK1    - Array of length KORDER.
   WK2    - Array of length KORDER.
   WK3    - Array of length KORDER.
 
2. Informational errors
   Type Code
     4   4  Multiplicity of the knots cannot exceed the order of
            the spline.
     4   5  The knots must be nondecreasing.
 
Keyword:    Differentiate
 
GAMS:       E3a2; K6a2
 
Chapter:    MATH/LIBRARY Interpolation and Approximation
 
Page No.:   MATH/LIBRARY User's Manual page 550