1CSA2S(3NCARG)                    NCAR GRAPHICS                   CSA2S(3NCARG)
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NAME

6       CSA2S  -  cubic  spline approximation, simple entry for two-dimensional
7       input, gridded output
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SYNOPSIS

10       CALL CSA2S (NI, XI, UI, KNOTS, NXO, ,NYO, XO, YO, UO, NWRK, WORK, IER)
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DESCRIPTION

13       NI          (integer,input) The number of input data points. It must be
14                   that  NI  .gt. 3 and, depending on the size of KNOTS below,
15                   NI may have to be larger.
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17       XI          (real, input) An array containing the X - Y coordinates  of
18                   the  input  data  points.  XI  is  dimensioned  for 2 x NI.
19                   XI(1,L) is the X coordinate and XI(2,L) is the Y coordinate
20                   for the input domain for L=1,NI.
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22       UI          (real,  input) An array dimensioned for NI containing func‐
23                   tion values at the input XI values, that is  UI(L)  is  the
24                   value   of   the   input   function   at   the   coordinate
25                   (XI(1,L),XI(2,L)) for L=1,NI.
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27       KNOTS       (integer, input) The number of knots to  be  used  in  con‐
28                   structing  the  approximation spline.  KNOTS is dimensioned
29                   for 2 and provides the number of knots to be used in the  X
30                   and  the  Y directions.  Both KNOTS(1) and KNOTS(2) must be
31                   at least 4.  The larger the values for  KNOTS,  the  closer
32                   the  approximated  curve  will  come to passing through the
33                   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       XO          (real, input) An array dimensioned for NXO containing the X
42                   coordinates of the output surface.
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44       YO          (real, input) An array dimensioned for NYO containing the Y
45                   coordinates of the output surface.
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47       UO          (real, output) An array dimensioned for NXO x NYO  contain‐
48                   ing  the calculated function values for the output surface.
49                   UO(I,J) is the calculated functional value at (XO(I),YO(J))
50                   for I=1,NXO and J=1,NYO.
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52       NWRK        (integer,  input) The size of the WORK array.  NWRK must be
53                   at least KNOTS(1)*KNOTS(2)*(KNOTS(1)*KNOTS(2)+3).
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55       WORK        (real, input) A work array dimensioned for NWRK.
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57       IER         (integer,  output)  An  error  return  value.   If  IER  is
58                   returned as 0, then no errors were detected. If IER is non-
59                   zero, then refer to the man  page  for  csagrid_errors  for
60                   details.
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USAGE

63       CSA2S  is called to find an approximating cubic spline surface for two-
64       dimensional input data.  If you want to weight the input  data  values,
65       calculate  derivatives, or handle data sparse areas specially, then you
66       will need to use CSA2XS.
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ACCESS

69       To use CSA2S, load the NCAR Graphics library ngmath.
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SEE ALSO

72       csagrid, csa2xs, csa2ls, csa2lxs
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74       Complete documentation for Csagrid is available at URL
75       http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html
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78       Copyright (C) 2000
79       University Corporation for Atmospheric Research
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81       The use of this Software is governed by a License Agreement.
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85UNIX                             January 1999                    CSA2S(3NCARG)
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