1CSA3LXS(3NCARG)                  NCAR GRAPHICS                 CSA3LXS(3NCARG)
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NAME

6       CSA3LXS  -  cubic spline approximation, expanded entry for three-dimen‐
7       sional input, list output
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SYNOPSIS

10       CALL CSA3LXS (NI, XI, UI, WTS, KNOTS, SMTH, NDERIV,
11                     NO, XO, YO, ZO, 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       WTS         (real,  input)  An  array  dimensioned  for  NI  containing
29                   weights  for the UI values at the input XI values, that is,
30                   WTS(L) is a weight for the value of UI(L) for  L=1,NI.   If
31                   you  do  not desire to weight the input UI values, then set
32                   WTS(1) to -1.  The weights in the WTS  array  are  relative
33                   and  may be set to any non-negative value.  When CSA3LXS is
34                   called, the weights are summed and the  individual  weights
35                   are normalized so that the weight sum is unity.
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37       KNOTS       (integer,  input)  The  number  of knots to be used in con‐
38                   structing the approximation spline.  KNOTS  is  dimensioned
39                   for 3 and provides the number of knots to be used in the X,
40                   Y, and  Z directions.  KNOTS(I) must  be  at  least  4  for
41                   I=1,3.   The  larger  the  values for KNOTS, the closer the
42                   approximated curve will come to passing through  the  input
43                   function values.
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45       SMTH        (real,  input) A parameter that controls extrapolation into
46                   data sparse regions.  If SMTH is zero, then nothing special
47                   is  done  in  data sparse regions.  A good first choice for
48                   SMTH is 1.
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50       NDERIV      (integer, input) An array dimensioned for 3 that specifies,
51                   for  each  coordinate,   whether you want functional values
52                   (=0), first derivative values (=1),  or  second  derivative
53                   values (=2).
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55       NO          (integer,  input)  The  number  of coordinate values in the
56                   output list.  NO can be any positive number.
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58       XO          (real, input) An array dimensioned for NO containing the  X
59                   coordinates of the output list.
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61       YO          (real,  input) An array dimensioned for NO containing the Y
62                   coordinates of the output list.
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64       ZO          (real, input) An array dimensioned for NO containing the  Z
65                   coordinates of the output list.
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67       UO          (real,  output)  An array dimensioned for NO containing the
68                   calculated function values for the output spline.  UO(I) is
69                   the  calculated functional value at (XO(I),YO(I),ZO(I)) for
70                   I=1,NO.
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72       NWRK        (integer, input) The size of the WORK array.  NWRK must  be
73                   at  least  NK  *  (NK+3)  where  NK = KNOTS(1) * KNOTS(2) *
74                   KNOTS(3).
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76       WORK        (real, input) A work array dimensioned for NWRK.
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78       IER         (integer,  output)  An  error  return  value.   If  IER  is
79                   returned as 0, then no errors were detected. If IER is non-
80                   zero, then refer to the man  page  for  csagrid_errors  for
81                   details.
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USAGE

84       CSA3LXS  is  called if you want to weight the input data values, calcu‐
85       late derivatives, or handle data sparse areas specially.  If you do not
86       want to do any of these three things, then use CSA3LS.
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ACCESS

89       To use CSA3LXS, load the NCAR Graphics library ngmath.
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SEE ALSO

92       csagrid, csa3s, csa3xs, csa3ls
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94       Complete documentation for Csagrid is available at URL
95       http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html
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98       Copyright (C) 2000
99       University Corporation for Atmospheric Research
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101       The use of this Software is governed by a License Agreement.
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105UNIX                             January 1999                  CSA3LXS(3NCARG)
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