1SURF2(3NCARG)                    NCAR GRAPHICS                   SURF2(3NCARG)
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NAME

6       SURF2 - 2D interpolation for gridded data
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SYNOPSIS

9       FUNCTION SURF2 (XX, YY, M, N, X, Y, Z, IZ, ZP, SIGMA)
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11       This  function  interpolates  a surface value at a specified coordinate
12       using bi-splines under tension. SURF1 must be  called  before  invoking
13       SURF2.  The  desired interpolated value is returned as the value of the
14       function.
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DESCRIPTION

17       XX          (real, input) Contains the X coordinate of a  point  to  be
18                   mapped onto the interpolated surface.
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20       YY          (real,  input)  Contains  the Y coordinate of a point to be
21                   mapped onto the interpolated surface.
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23       M           (integer, input) The number of grid lines in the  X  direc‐
24                   tion. (M > 1)
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26       N           (integer,  input)  The number of grid lines in the Y direc‐
27                   tion. (N > 1)
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29       X           (real, input) An array containing M X coordinates for  grid
30                   lines  in  the  X  direction. These values must be strictly
31                   increasing.
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33       Y           (real, input) An array containing N Y coordinates for  grid
34                   lines  in  the  Y  direction. These values must be strictly
35                   increasing.
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37       Z           (real, input) An array containing M x N  functional  values
38                   at the grid points; Z(I,J) contains the functional value at
39                   (X(I),Y(J)) for I=1,M and J=1,N.
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41       IZ          (integer, input) The row dimension of the matrix Z  (IZ  is
42                   greater than or equal to M).
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44       ZP          (real, input) An array of size M x N x 3.
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46       SIGMA       (real,  input) Tension factor. Values near zero result in a
47                   cubic spline; large values (e.g. 50)  result  in  nearly  a
48                   polygonal line. A typical value is 1.
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RETURN VALUE

51       SURF2 returns the interpolated value at the specified point T.
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ACCESS

54       To use SURF2, load the NCAR Graphics library ngmath.
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SEE ALSO

57       surf1, fitgrid_params.
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59       Complete documentation for Fitgrid is available at URL
60       http://ngwww.ucar.edu/ngdoc/ng/ngmath/fitgrid/fithome.html
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63       Copyright (C) 2000
64       University Corporation for Atmospheric Research
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66       The use of this Software is governed by a License Agreement.
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70UNIX                              March 1998                     SURF2(3NCARG)
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