1c_csa3ls(3NCARG)                 NCAR GRAPHICS                c_csa3ls(3NCARG)
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NAME

6       c_csa3ls  -  cubic  spline approximation, simple entry for three-dimen‐
7       sional input, list output
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FUNCTION PROTOTYPE

10       float *c_csa3ls(int, float [], float [], float [], float [],
11                       int [], int, float [], float [], float[], int *);
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SYNOPSIS

15       float *c_csa3ls(int n, float xi[], float yi[], float zi[], float ui[],
16                       int knots[3], int no, float xo[], float yo[], float zo[],
17                       int *);
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DESCRIPTION

21       n           (integer,input) The number of input data points. It must be
22                   that  n  is  greater  than  3 and, depending on the size of
23                   knots below, n may have to be larger.
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25       xi          (real, input) An array dimensioned for n containing  the  X
26                   coordinate values for the input function.
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28       yi          (real,  input)  An array dimensioned for n containing the Y
29                   coordinate values for the input function.
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31       zi          (real, input) An array dimensioned for n containing  the  Z
32                   coordinate values for the input function.
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34       ui          (real,  input) An array containing the functional values of
35                   the input function -- ui[k]  is  the  functional  value  at
36                   (xi[k], yi[k], zi[k]) for k=0,n-1.
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38       knots       (integer,  input)  The  number  of knots to be used in con‐
39                   structing the approximation  spline.   knots[0],  knots[1],
40                   and  knots[2]  must be at least 4. The larger the value for
41                   knots, the closer the approximated curve will come to pass‐
42                   ing through the input function values.
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44       no          (integer,  input)  The number of X - Y coordinate values to
45                   be calculated for the output array.
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47       xo          (real, input) An array dimensioned for no containing the  X
48                   coordinates of the output list.
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50       yo          (real, output) An array dimensioned for no containing the Y
51                   coordinates of the output list.
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53       zo          (real, output) An array dimensioned for no containing the Z
54                   coordinates of the output list.
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56       ier         (pointer to integer, output) An error return value. If *ier
57                   is returned as 0, then no errors were detected. If *ier  is
58                   non-zero,  then  refer to the error list in the error table
59                   for details.
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USAGE

62       c_csa3ls is called to find values of an approximating cubic  spline  at
63       specified  three-dimensional  coordinates.   If  you want to weight the
64       input data values, calculate derivatives, or handle data  sparse  areas
65       specially, then you will need to use c_csa3lxs.
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67       c_csa3ls  returns a pointer to a linear array of data that contains the
68       approximated values calculated at the input list of coordinate  values.
69       That is, if out is declared as
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71         float *out;
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73       and we set:
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75         out = c_csa3ls(n, x, y, z, u, knots, no, xo, yo, zo, &ier);
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77       then  out[i]  is  the  approximated  function value at coordinate point
78       (xo[i], yo[i], zo[i]) for 0 <= i < no. The space for out  is  allocated
79       internal to c_csa3ls and is no floats in size.
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ACCESS

82       To use c_csa3ls, load the NCAR Graphics library ngmath.
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SEE ALSO

85       csagrid, c_csa3s, c_csa3xs, c_csa3lxs
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87       Complete documentation for Csagrid is available at URL
88       http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html
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91       Copyright (C) 2000
92       University Corporation for Atmospheric Research
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94       The use of this Software is governed by a License Agreement.
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98UNIX                             January 1999                 c_csa3ls(3NCARG)
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