GRASS Programmer's Manual
6.4.2(2012)
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gammavol.c
Go to the documentation of this file.
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/****************************************************************************
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* MODULE: R-Tree library
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*
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* AUTHOR(S): Antonin Guttman - original code
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* Daniel Green (green@superliminal.com) - major clean-up
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* and implementation of bounding spheres
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*
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* PURPOSE: Multidimensional index
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*
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* COPYRIGHT: (C) 2001 by the GRASS Development Team
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*
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* This program is free software under the GNU General Public
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* License (>=v2). Read the file COPYING that comes with GRASS
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* for details.
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*****************************************************************************/
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#include <stdio.h>
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#include <math.h>
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#include <grass/gis.h>
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#ifndef ABS
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# define ABS(a) ((a) > 0 ? (a) : -(a))
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#endif
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#define EP .0000000001
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double
sphere_volume
(
double
dimension)
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{
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double
log_gamma, log_volume;
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log_gamma = lgamma(dimension / 2.0 + 1);
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log_volume = dimension / 2.0 *
log
(M_PI) - log_gamma;
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return
exp(log_volume);
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}
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int
main
()
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{
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double
dim = 0, delta = 1;
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while
(
ABS
(delta) >
EP
)
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if
(
sphere_volume
(dim + delta) >
sphere_volume
(dim))
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dim += delta;
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else
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delta /= -2;
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fprintf(stdout,
"max volume = %.10f at dimension %.10f\n"
,
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sphere_volume
(dim), dim);
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return
0;
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}
lib
vector
rtree
gammavol.c
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