1c_ftkurvpd(3NCARG) NCAR GRAPHICS c_ftkurvpd(3NCARG)
2
6 c_ftkurvpd - interpolation and derivative calculation for closed para‐
7 metric curves
8
10 int c_ftkurvpd (int, float [], float [], int, float [],
11 float [], float [], float [], float [],
12 float [], float []);
13
15 int c_ftkurvpd (n, xi, yi, m, t, xo, yo, xd, yd, xdd, ydd);
16
18 n The number of input data points. (n > 1)
19 xi An array containing the abscissae for the input function.
21 yi An array containing the functional values (y[k] is the
23 functional value at x[k] for k=0,n).
24 m The number of desired interpolated points.
26 t Contains an array of values for the parameter mapping onto
28 the interpolated curve. Any interval [tt,tt+1.] maps onto
29 the entire curve.
30 xo An array containing the X values for the interpolated
32 points. t[k] maps to (xo[k],yo[k]) for k=0,n-1.
33 yo An array containing the Y values for the interpolated
35 points.
36 xd Contains the first derivatives of the X component with
38 respect to t.
39 yd Contains the first derivatives of the Y component with
41 respect to t.
42 xdd Contains the second derivatives of the X component with
44 respect to t.
45 ydd Contains the second derivatives of the Y component with
47 respect to t.
48
50 c_ftkurvpd returns an error value as per:
51 = 0 -- no error.
53 = 1 -- if n is less than 2.
54 = 2 -- if adjacent coordinate pairs coincide.
55
57 This procedure behaves like ftkurvp except that in addition it returns
58 the first and second derivatives of the component functions in the
59 parameterization.
60 Given a sequence of distinct input points ( (x[0],y[0]), ... ,
62 (x[n-1],y[n-1]), the interpolated curve is parameterized by mapping
63 points in the interval [0.,1.] onto the interpolated curve. The result‐
64 ing curve has a parametric representation both of whose components are
65 splines under tension and functions of the polygonal arc length. The
66 value 0. is mapped onto (x[0],y[0]) and the value 1. is mapped onto
67 (x[0],y[0]) as well (completing the closed curve).
68 c_ftkurvpd is called after all of the desired values for control param‐
70 eters have been set using the procedures c_ftseti, c_ftsetr, c_ftsetc.
71 The only control parameter that applies to c_ftkurvpd is: sig.
72 The value for the parameter sig specifies the tension factor. Values
74 near zero result in a cubic spline; large values (e.g. 50) result in
75 nearly a polygonal line. A typical value is 1. (the default).
76
78 To use c_ftkurvpd, load the NCAR Graphics library ngmath.
79
81 fitgrid_params, c_ftseti, c_ftsetr, c_ftsetc.
82 Complete documentation for Fitgrid is available at URL
84 http://ngwww.ucar.edu/ngdoc/ng/ngmath/fitgrid/fithome.html
85
87 Copyright (C) 2000
88 University Corporation for Atmospheric Research
89 This documentation is free software; you can redistribute it and/or
91 modify it under the terms of the GNU General Public License as pub‐
92 lished by the Free Software Foundation; either version 2 of the
93 License, or (at your option) any later version.
94 This software is distributed in the hope that it will be useful, but
96 WITHOUT ANY WARRANTY; without even the implied warranty of MER‐
97 CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
98 Public License for more details.
99 You should have received a copy of the GNU General Public License along
101 with this software; if not, write to the Free Software Foundation,
102 Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
103UNIX March 1998 c_ftkurvpd(3NCARG)