1CURVS2(3NCARG) NCAR GRAPHICS CURVS2(3NCARG)
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6 CURVS2 - calculates an interpolated value for a smoothing spline under
7 tension at a given point.
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10 FUNCTION CURVS2(T,N,PARAM,X,Y,XP,YP,SIGMA,XO,YO)
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12 This subroutine is a companion to CURV1S which must be called before
13 calling this subroutine. CURV2S calculates an interpolated value for a
14 smoothing spline under tension at a given point.
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17 T (real, input) A real value to be mapped onto the interpo‐
18 lating curve. Values of T between zero and one interpolate
19 the original data; any values of T outside this range
20 result in extrapolation.
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22 N (integer, input) The number of points which were specified
23 to determine the curve in CURVS1.
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25 PARAM (real, input) The arc lengths as computed by CURVS1.
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27 X (real, input) An array containing the X-coordinate values
28 of the specified points.
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30 Y (real, input) An array containing the Y-coordinate values
31 of the specified points.
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33 XP (real, input) An array of second derivative values as cal‐
34 culated by CURVS1.
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36 YP (real, input) An array of second derivative values as cal‐
37 culated by CURVS1.
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39 SIGMA (real, input) Tension factor. Values near zero result in a
40 cubic spline; large values (e.g. 50) result in nearly a
41 polygonal line. A typical value is 1.
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43 XO (real, output) The interpolated X value.
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45 YO (real, output) The interpolated Y value.
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48 To use CURV2, load the NCAR Graphics library ngmath.
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51 curvs1, fitgrid_params.
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53 Complete documentation for Fitgrid is available at URL
54 http://ngwww.ucar.edu/ngdoc/ng/ngmath/fitgrid/fithome.html
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57 Copyright (C) 2000
58 University Corporation for Atmospheric Research
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60 The use of this Software is governed by a License Agreement.
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64UNIX August 2002 CURVS2(3NCARG)