1KURVP1(3NCARG) NCAR GRAPHICS KURVP1(3NCARG)
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6 KURVP1 - calculate values for KURVP2 usage
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9 CALL KURVP1 (N, X, Y, XP, YP, TEMP, S, SIGMA, IER)
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11 This subroutine calculates certain values that are used by KURVP2 in
12 order to compute an interpolatory spline under tension through a
13 sequence of points in the plane that form a closed curve. The actual
14 computation of the interpolated values must be done using KURVP2 .
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17 N (integer,input) The number of input data points. (N > 1)
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19 X (real,input) An array containing the X values of the
20 points.
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22 Y (real,input) An array containing the Y values of the
23 points. Adjacent pairs of points must be distinct.
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25 XP (real,output) An array of length N.
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27 YP (real,output) An array of length N.
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29 TEMP (real,input) Scratch space.
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31 S (real,output) An array of length N (this will be used to
32 pass to KURVP2).
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34 SIGMA (real,input) Tension factor. Values near zero result in a
35 cubic spline; large values (e.g. 50) result in nearly a
36 polygonal line. A typical value is 1.
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38 IER (integer,output) An error return value. If IER is returned
39 as 0, then no errors were detected.
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41 = 1 if N is less than 2.
42 = 2 if a pair of adjacent points coincide.
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45 To use KURVP1, load the NCAR Graphics library ngmath.
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48 kurvp2, fitgrid_params.
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50 Complete documentation for Fitgrid is available at URL
51 http://ngwww.ucar.edu/ngdoc/ng/ngmath/fitgrid/fithome.html
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54 Copyright (C) 2000
55 University Corporation for Atmospheric Research
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57 The use of this Software is governed by a License Agreement.
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61UNIX March 1998 KURVP1(3NCARG)