1c_csa2ls(3NCARG)                 NCAR GRAPHICS                c_csa2ls(3NCARG)
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NAME

6       c_csa2ls - cubic spline approximation, simple entry for two-dimensional
7       input, list output
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FUNCTION PROTOTYPE

10       float *c_csa2ls(int, float [], float [], float [], int [],
11                       int, float [], float [], int *);
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SYNOPSIS

15       int c_csa2ls(int n, float xi[], float yi[], float zi[], int knots[2],
16                   int no, float xo[], float yo[], int *ier);
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DESCRIPTION

20       n           (integer,input) The number of input data points. It must be
21                   that  n  is  greater  than  3 and, depending on the size of
22                   knots below, n may have to be larger.
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24       xi          (real, input) An array dimensioned for n containing  the  X
25                   coordinate values for the input function.
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27       yi          (real,  input)  An array dimensioned for n containing the Y
28                   coordinate values for the input function.
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30       zi          (real, input) An array containing the functional values  of
31                   the  input  function  --  zi[k]  is the functional value at
32                   (xi[k], yi[k]) for k=0,n-1.
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34       knots       (integer, input) The number of knots to  be  used  in  con‐
35                   structing  the approximation spline.  knots[0] and knots[1]
36                   must be at least 4. The larger the  value  for  knots,  the
37                   closer  the approximated curve will come to passing through
38                   the input function values.
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40       no          (integer, input) The number of X - Y coordinate  values  to
41                   be calculated for the output array.
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43       xo          (real,  input) An array dimensioned for no containing the X
44                   coordinates of the output list.
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46       yo          (real, output) An array dimensioned for no containing the Y
47                   coordinates of the output list.
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49       ier         (pointer to integer, output) An error return value. If *ier
50                   is returned as 0, then no errors were detected. If *ier  is
51                   non-zero,  then  refer to the error list in the error table
52                   for details.
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USAGE

55       c_csa2ls is called to find values of an approximating cubic  spline  at
56       specified  two-dimensional coordinates. If you want to weight the input
57       data values, calculate derivatives, or handle data  sparse  areas  spe‐
58       cially, then you will need to use c_csa2lxs.
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60       c_csa2ls  returns a pointer to a linear array of data that contains the
61       approximated values calculated at the input list of coordinate  values.
62       That is, if out is declared as
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64         float *out;
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66       and we set:
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68         out = c_csa2ls(n, x, y, z, knots, no, xo, yo, &ier);
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70       then  out[i]  is  the  approximated  function value at coordinate point
71       (xo[i], yo[i]) for 0 <= i < no. The space for out is allocated internal
72       to c_csa2ls and is no floats in size.
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ACCESS

75       To use c_csa2ls, load the NCAR Graphics library ngmath.
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SEE ALSO

78       csagrid, c_csa2s, c_csa2xs, c_csa2lxs
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80       Complete documentation for Csagrid is available at URL
81       http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html
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84       Copyright (C) 2000
85       University Corporation for Atmospheric Research
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87       The use of this Software is governed by a License Agreement.
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91UNIX                             January 1999                 c_csa2ls(3NCARG)
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