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

6       CURVD - derivatives for 1D functions.
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SYNOPSIS

9       FUNCTION CURVD (T, N, X, Y, YP, SIGMA)
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11       This  function  calculates  a  derivative  at a specified point using a
12       spline under tension.  CURV1 must be called prior to calling CURVD, and
13       the  values  thus obtained used as input to CURVD. The derivative value
14       is returned.
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DESCRIPTION

17       T           (real, input) The abscissa for which an interpolated  func‐
18                   tion value is desired.
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20       N           (integer, input) The number of input data values. (N > 1)
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22       X           (real,  input)  An  array  containing the abscissae for the
23                   input function.
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25       Y           (real, input) An array containing the functional values  of
26                   the  input data -- Y(K) is the functional value at X(K) for
27                   K=1,N.
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29       YP          (real, input) Contains values for the second derivative (as
30                   calculated by CURV1).
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32       SIGMA       (real,  input) Tension factor. Values near zero result in a
33                   cubic spline; large values (e.g. 50)  result  in  nearly  a
34                   polygonal line. A typical value is 1.
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RETURN VALUE

37       CURVD  returns  the  derivative  value of the interpolated curve at the
38       specified point T.
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ACCESS

41       To use CURVD, load the NCAR Graphics library ngmath.
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SEE ALSO

44       curv1, fitgrid_params.
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46       Complete documentation for Fitgrid is available at URL
47       http://ngwww.ucar.edu/ngdoc/ng/ngmath/fitgrid/fithome.html
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50       Copyright (C) 2000
51       University Corporation for Atmospheric Research
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53       The use of this Software is governed by a License Agreement.
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57UNIX                              March 1998                     CURVD(3NCARG)
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