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

6       c_shgetnp - find the nearest points to a specified point in 3-space
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FUNCTION PROTOTYPE

9       int c_shgetnp(float, float, float, int, float *, float *, float *,
10                     int, int *);
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SYNOPSIS

14       int c_shgetnp (px, py, pz, n, x[], y[], z[], iflag, ier );
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DESCRIPTION

18       px          (float)  The X coordinate value for a point P whose nearest
19                   neighbor is to be found.
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21       py          (float) The Y coordinate value for a point P whose  nearest
22                   neighbor is to be found.
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24       pz          (float)  The Z coordinate value for a point P whose nearest
25                   neighbor is to be found.
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27       n           (int) The number of input data points, n > 1.
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29       x           (float) An array of length n containing  the  X  coordinate
30                   values for the input data points.
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32       y           (float)  An  array  of length n containing the Y coordinate
33                   values for the input data points.
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35       z           (float) An array of length n containing  the  Z  coordinate
36                   values for the input data points.
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38       iflag       (int)  A  flag  that  equals 0 if this is the first call to
39                   this subroutine for the given dataset and equals  1  other‐
40                   wise.
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42       ier         (pointer  to  int)  An  error  return  value.   If  *ier is
43                   returned as 0, then no errors were  detected.  If  *ier  is
44                   non-zero,  then  look at the man page for shgrid_errors for
45                   details.
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USAGE

48       c_shgetnp is called to find the nearest point to a specified  point  in
49       3-space. Successive calls to c_shgetnp will determine the point nearest
50       the specified point exclusive of the points found  in  previous  calls,
51       i.e.  successive calls can be used to find the N nearest points for any
52       N between one and the maximum number of points in the input dataset.
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54       c_shgetnp returns an integer, say np, such that (x[np],y[np],z[np])  is
55       the nearest input data point to P. np = -1 if *ier is not zero. On suc‐
56       cessive calls to this function after the first (that is  when  iflag=1)
57       you can find the Mth closest point to (px,py,pz) with the Mth call.
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ACCESS

60       To use c_shgetnp, load the NCAR Graphics library ngmath.
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SEE ALSO

63       shgetnp, c_shgrid, c_shseti, c_shgeti, shgrid_params.
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65       Complete documentation for Sh is available at URL
66       http://ngwww.ucar.edu/ngdoc/ng/ngmath/shgrid/shhome.html
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69       Copyright (C) 2000
70       University Corporation for Atmospheric Research
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72       This  documentation  is  free  software; you can redistribute it and/or
73       modify it under the terms of the GNU General  Public  License  as  pub‐
74       lished  by  the  Free  Software  Foundation;  either  version  2 of the
75       License, or (at your option) any later version.
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77       This software is distributed in the hope that it will  be  useful,  but
78       WITHOUT  ANY  WARRANTY;  without  even  the  implied  warranty  of MER‐
79       CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  General
80       Public License for more details.
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82       You should have received a copy of the GNU General Public License along
83       with this software; if not, write  to  the  Free  Software  Foundation,
84       Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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89UNIX                             January 1999                c_shgetnp(3NCARG)
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