Banfac Banslv Bint4 Bintk Bspldr Bsplev Bsplpp Bsplvd Bsplvn Bvalue Interv Ppvalu

Bvalue() Function Bvalue ( T() As  Double, A() As  Double, N As  Long, K As  Long, Ideriv As  Long, X As  Double, Inbv As  Long, Info As  Long  ) Evaluation of function or derivative value for B-representation of B-spline Purpose This routine evaluates the B-representation (T(), A(), N, K) of a B-spline at X for the function value on Ideriv = 0 or any of its derivatives on Ideriv = 1, 2, ..., K-1. Right limiting values (right derivatives) are returned except at the right end point X = T(N) where left limiting values are computed. The spline is defined on T(K-1) <= X <= T(N). Bvalue returns a fatal error when X is outside of this interval. To compute left derivatives or left limiting values at a knot T(i), replace N by i-1 and set X = T(i), i = K to N. Returns Double Value of the Ideriv-th derivative at X. Parameters [in] T() Array T(LT - 1) (LT >= N + K) Knot vector. [in] A() Array A(LA - 1) (LA >= N) B-spline coefficient array. [in] N Number of B-spline coefficients. (N = sum of knot multiplicities - K) [in] K Order of the B-spline. (K >= 1) [in] Ideriv Order of the derivative. (0 <= Ideriv <= K - 1) If Ideriv = 0, returns the B-spline value. [in] X Argument x. (T(K-1) <= X <= T(N)) [in,out] Inbv An initialization parameter. [in] Must be set to 1 when the first time Bvalu is called. [out] Information for efficient processing after the initial call and Inbv must not be changed by the user. Distinct splines require distinct Inbv parameters. [out] Info = 0: Successful exit. = -1: The argument T() is invalid. = -2: The argument A() is invalid. = -3: The argument N had an illegal value. (N < K) = -4: The argument K had an illegal value. (K < 1) = -5: The argument Ideriv had an illegal value. (Ideriv < 0 or Ideriv >= K) = -6: The argument X had an illegal value. (X < T(K-1) or X > T(N)) = 1: A left limiting value cannot be obtained at T(K-1). Reference SLATEC Example Program See example of Bint4.