1CURVP1(3NCARG)                   NCAR GRAPHICS                  CURVP1(3NCARG)
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NAME

6       CURVP1 - calculate values for CURVP2 usage.
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SYNOPSIS

9       CALL CURVP1 (N, X, Y, P, YP, TEMP, SIGMA, IER)
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11       This  subroutine  calculates  certain values that are used by CURVP2 in
12       order to compute  an  interpolatory  spline  under  tension  through  a
13       sequence  of functional values for a periodic function. The actual com‐
14       putation of the interpolated values must be done using CURVP2 .
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DESCRIPTION

17       N           (integer, input) The number of input data values. (N > 1)
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19       X           (real, input) An array containing  the  abscissae  for  the
20                   input function.
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22       Y           (real,  input) An array containing the functional values of
23                   the input function -- Y(K) is the functional value at  X(K)
24                   for K=1,N.
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26       P           (real, input) The period of the function. P must be greater
27                   than X(N)-X(1).
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29       YP          (real, output) Contains values for  the  second  derivative
30                   (these are calculated by CURVP1).
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32       TEMP        (real, input) Scratch space.
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34       SIGMA       (integer, input) Tension factor. Values near zero result in
35                   a 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 P is less than or equal to X(N)-X(1).
43                   = 3 if the X values are not strictly increasing.
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ACCESS

46       To use CURVP1, load the NCAR Graphics library ngmath.
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SEE ALSO

49       curvp2, fitgrid_params.
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51       Complete documentation for Fitgrid is available at URL
52       http://ngwww.ucar.edu/ngdoc/ng/ngmath/fitgrid/fithome.html
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55       Copyright (C) 2000
56       University Corporation for Atmospheric Research
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58       This documentation is free software; you  can  redistribute  it  and/or
59       modify  it  under  the  terms of the GNU General Public License as pub‐
60       lished by the  Free  Software  Foundation;  either  version  2  of  the
61       License, or (at your option) any later version.
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63       This  software  is  distributed in the hope that it will be useful, but
64       WITHOUT ANY  WARRANTY;  without  even  the  implied  warranty  of  MER‐
65       CHANTABILITY  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
66       Public License for more details.
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68       You should have received a copy of the GNU General Public License along
69       with  this  software;  if  not,  write to the Free Software Foundation,
70       Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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75UNIX                              March 1998                    CURVP1(3NCARG)
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