GRASS GIS 7 Programmer's Manual
7.8.2(2019)-exported
gauss.c
Go to the documentation of this file.
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#include <math.h>
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#include <grass/gmath.h>
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/*!
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* \fn double G_math_rand_gauss(const int seed, const double sigma)
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*
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* \brief Gaussian random number generator
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*
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* Gaussian random number generator (mean = 0.0)
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*
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* \param[in] seed
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& \param[in] sigma
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* \return double
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*/
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double
G_math_rand_gauss
(
double
sigma)
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{
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double
x
, y, r2;
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do
{
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/* choose x,y in uniform square (-1,-1) to (+1,+1) */
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x
= -1 + 2 *
G_math_rand
();
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y = -1 + 2 *
G_math_rand
();
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/* see if it is in the unit circle */
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r2 =
x
*
x
+ y * y;
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}
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while
(r2 > 1.0 || r2 == 0);
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/* Box-Muller transform */
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return
sigma * y * sqrt(-2.0 * log(r2) / r2);
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}
x
#define x
G_math_rand
float G_math_rand(void)
Definition:
rand1.c:17
G_math_rand_gauss
double G_math_rand_gauss(double sigma)
Definition:
gauss.c:17
gmath
gauss.c
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