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.\"
.\" $Id: c_ftkurvp.m,v 1.4 2008-07-27 03:35:38 haley Exp $
.\"
.TH c_ftkurvp 3NCARG "March 1998" UNIX "NCAR GRAPHICS"
.SH NAME
c_ftkurvp - interpolation for closed parametric curves
.SH FUNCTION PROTOTYPE
int c_ftkurvp (int, float [], float [], int, float [], float [], float []);
.SH SYNOPSIS
int c_ftkurvp (n, xi, yi, m, t, xo, yo);
.SH DESCRIPTION
.IP n 12
The number of input data values. (n > 1)
.IP xi 12
An array containing the abscissae for the input function.
.IP yi 12
An array containing the functional values (y[k] is the
functional value at x[k] for k=0,n-1).
.IP m 12
The number of desired interpolated values.
.IP t 12
Contains an array of values for the parameter mapping onto the
interpolated curve. Any interval [tt,tt+1.] maps onto the entire curve.
.IP xo 12
An array containing the X values for the interpolated points.
t[k] maps to (xo[k],yo[k]) for k=0,m-1.
.IP yo 12
An array containing the Y values for the interpolated points.
t[k] maps to (xo[k],yo[k]) for k=0,m-1.
.SH RETURN VALUE
c_ftkurvp returns an error value as per:
.br
.sp
= 0 -- no error.
.br
= 1 -- if n is less than 2.
.br
= 2 -- if adjacent coordinate pairs coincide.
.br
.SH USAGE
This procedure calculates an interpolatory spline under tension through
a sequence of points in the plane forming a closed curve.
.sp
Given a sequence of distinct input points
( (x[0],y[0]), ... , (x[n-1],y[n-1]), the interpolated curve is
parameterized by mapping points in the interval [0.,1.] onto the
interpolated curve. The resulting curve
has a parametric representation both of whose components are
splines under tension and functions of the
polygonal arc length. The value 0. is mapped onto
(x[0],y[0]) and the value 1. is mapped onto
(x[0],y[0]) as well (completing the closed curve).
.sp
c_ftkurvp is called after all of the desired values for control parameters
have been set using the
procedures c_ftseti, c_ftsetr, c_ftsetc. The only control parameter that
applies to c_ftkurvp is: sig.
.sp
The value for the parameter sig specifies the tension factor. Values
near zero result in a cubic spline;
large values (e.g. 50) result in nearly a polygonal line. A typical
value is 1. (the default).
.SH ACCESS
To use c_ftkurvp, load the NCAR Graphics library ngmath.
.SH SEE ALSO
fitgrid_params, c_ftseti, c_ftsetr, c_ftsetc.
.sp
Complete documentation for Fitgrid is available at URL
.br
http://ngwww.ucar.edu/ngdoc/ng/ngmath/fitgrid/fithome.html
.SH COPYRIGHT
Copyright (C) 2000
.br
University Corporation for Atmospheric Research
.br
The use of this Software is governed by a License Agreement.
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