1CSA3S(3NCARG)                    NCAR GRAPHICS                   CSA3S(3NCARG)
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NAME

6       CSA3S  - cubic spline approximation, simple entry for three-dimensional
7       input
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SYNOPSIS

10       CALL CSA3S (NI, XI, UI, KNOTS, NXO, NYO, NZO, XO, YO, ZO,
11                   UO, NWRK, WORK, IER)
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DESCRIPTION

14       NI          (integer,input) The number of input data points. It must be
15                   that  NI  .gt. 3 and, depending on the size of KNOTS below,
16                   NI may have to be larger.
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18       XI          (real, input) An array containing the X - Y - Z coordinates
19                   of  the  input  data points.  XI is dimensioned for 3 x NI.
20                   XI(1,L) is the X coordinate, XI(2,L) is the  Y  coordinate,
21                   and  XI(2,L)  is  the Z coordinate for the input domain for
22                   L=1,NI.
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24       UI          (real, input) An array dimensioned for NI containing  func‐
25                   tion  values  at the input XI values, that is, UI(L) is the
26                   value of the input function at XI(L) for L=1,NI.
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28       KNOTS       (integer, input) An array dimensioned for 3 containing  the
29                   number of knots to be used in each coordinate direction for
30                   constructing the approximation spline.  KNOTS(I) must be at
31                   least  4  for  I=1,3.   The larger the value for KNOTS, the
32                   closer the approximated curve will come to passing  through
33                   the input function values.
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35       NXO         (integer,  input)  The number of X coordinate values in the
36                   output grid.
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38       NYO         (integer, input) The number of Y coordinate values  in  the
39                   output grid.
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41       NZO         (integer,  input)  The number of Z coordinate values in the
42                   output grid.
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44       XO          (real, input) An array dimensioned for NXO containing the X
45                   coordinates of the output surface.
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47       YO          (real, input) An array dimensioned for NYO containing the Y
48                   coordinates of the output surface.
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50       ZO          (real, input) An array dimensioned for NZO containing the Y
51                   coordinates of the output surface.
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53       UO          (real,  output)  An  array  dimensioned for NXO x NYO x NZO
54                   containing the calculated function values  for  the  output
55                   function.   UO(I,J,K) is the calculated functional value at
56                   (XO(I), YO(J), ZO(K)) for I=1,NXO and J=1,NYO and K=1,NZO.
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58       NWRK        (integer, input) The size of the WORK array.  NWRK must  be
59                   at  least  NK  *  (NK+3)  where  NK = KNOTS(1) * KNOTS(2) *
60                   KNOTS(3).
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62       WORK        (real, input) A work array dimensioned for NWRK.
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64       IER         (integer,  output)  An  error  return  value.   If  IER  is
65                   returned as 0, then no errors were detected. If IER is non-
66                   zero, then refer to the man  page  for  csagrid_errors  for
67                   details.
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USAGE

70       CSA3S  is called to find an approximating cubic spline for three-dimen‐
71       sional input data.  If you want to weight the input data values, calcu‐
72       late  derivatives, or handle data sparse areas specially, then you will
73       need to use CSA3S.
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ACCESS

76       To use CSA3XS, load the NCAR Graphics library ngmath.
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SEE ALSO

79       csagrid, csa3xs, csa3ls, csa3lxs
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81       Complete documentation for Csagrid is available at URL
82       http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html
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85       Copyright (C) 2000
86       University Corporation for Atmospheric Research
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88       The use of this Software is governed by a License Agreement.
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92UNIX                             January 1999                    CSA3S(3NCARG)
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