banfac banslv bint4 bintk bspldr bsplev bsplpp bsplvd bsplvn bvalue interv ppvalu

ppvalu() double ppvalu ( int  ldc, double  c[], double  xi[], int  lxi, int  k, int  ideriv, double  x, int *  inppv, int *  info  ) Evaluation of function or derivative value for PP (piecewise polynomial) form of B-spline Purpose This routine evaluates the PP (piecewise polynomial) representation (c[][], xi[], lxi, 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. The Taylor expansion about xi[j-1] for x in the interval xi[j-1] <= x < xi[j] is evaluated (j = 1 to lxi). Right limiting values (right derivatives) are obtained. ppvalu will extrapolate beyond xi[0] and xi[lxi]. To obtain left limiting values (left derivatives) at a xi[j], replace lxi by by j-1 and set x = xi[j], j = 1 to lxi. Returns Value of the ideriv-th derivative at x. Parameters [in] ldc Leading dimension of the two dimensional array c[][] (ldc >= k) [in] c[][] Array c[lc][ldc] (lc >= lxi) Right derivatives at break points. [in] xi[] Array xi[l_xi] (l_xi >= lxi + 1) Break points. [in] lxi Number of polynomial pieces. [in] k Order of B-spline. (k >= 1) [in] ideriv Order of the derivative. (0 <= ideriv <= k - 1) ideriv = 0 gives the B-spline value. [in] x Argument. (xi[0] <= x <= xi[lxi]) [in,out] inppv An initialization parameter. [in] Must be set to 1 when the first time ppvalu is called. [out] Information for efficient processing after the initial call and inppv must not be changed by the user. Distinct splines require distinct inppv parameters. [out] info = 0: Successful exit = -1: The argument ldc had an illegal value (ldc < k) = -4: The argument lxi had an illegal value (lxi < 1) = -5: The argument k had an illegal value (k < 1) = -6: The argument ideriv had an illegal value (ideriv < 0 or ideriv >= k) Reference SLATEC