1CSA2LS(3NCARG)                   NCAR GRAPHICS                  CSA2LS(3NCARG)
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NAME

6       CSA2LS  -  cubic spline approximation, simple entry for two-dimensional
7       input, list output
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SYNOPSIS

10       CALL CSA2LS (NI, XI, UI, KNOTS, NO, XO, YO, UO, NWRK,
11                    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 coordinates  of
19                   the  input  data  points.  XI  is  dimensioned  for 2 x NI.
20                   XI(1,L) is the X coordinate and XI(2,L) is the Y coordinate
21                   for the input domain for L=1,NI.
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23       UI          (real,  input) An array dimensioned for NI containing func‐
24                   tion values at the input XI values, that is  UI(L)  is  the
25                   value   of   the   input   function   at   the   coordinate
26                   (XI(1,L),XI(2,L)) for L=1,NI.
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28       KNOTS       (integer, input) The number of knots to  be  used  in  con‐
29                   structing  the  approximation spline.  KNOTS is dimensioned
30                   for 2 and provides the number of knots to be used in the  X
31                   and  the  Y directions.  Both KNOTS(1) and KNOTS(2) must be
32                   at least 4.  The larger the values for  KNOTS,  the  closer
33                   the  approximated  curve  will  come to passing through the
34                   input function values.
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36       NO          (integer, input) The number of  coordinate  values  in  the
37                   output list.  NO can be any positive number.
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39       XO          (real,  input) An array dimensioned for NO containing the X
40                   coordinates of the output list.
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42       YO          (real, input) An array dimensioned for NO containing the  Y
43                   coordinates of the output list.
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45       UO          (real,  output)  An array dimensioned for NO containing the
46                   calculated function values for the output spline.  UO(I) is
47                   the   calculated  functional  value  at  (XO(I),YO(I))  for
48                   I=1,NO.
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50       NWRK        (integer, input) The size of the WORK array.  NWRK must  be
51                   at least KNOTS(1)*KNOTS(2)*(KNOTS(1)*KNOTS(2)+3).
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53       WORK        (real, input) A work array dimensioned for NWRK.
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55       IER         (integer,  output)  An  error  return  value.   If  IER  is
56                   returned as 0, then no errors were detected. If IER is non-
57                   zero,  then  refer  to  the man page for csagrid_errors for
58                   details.
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USAGE

61       CSA2LS is called to find an approximating cubic spline surface for two-
62       dimensional input data with output values calculated at a list of user-
63       specified points.  If you want to weight the input data values,  calcu‐
64       late  derivatives, or handle data sparse areas specially, then you will
65       need to use CSA2LXS.
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ACCESS

68       To use CSA2LS, load the NCAR Graphics library ngmath.
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SEE ALSO

71       csagrid, csa2s, csa2xs, csa2ls,
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73       Complete documentation for Csagrid is available at URL
74       http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html
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77       Copyright (C) 2000
78       University Corporation for Atmospheric Research
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80       The use of this Software is governed by a License Agreement.
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84UNIX                             January 1999                   CSA2LS(3NCARG)
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