AlgRand

Files
file	AlgRand.c
	Provides functions which produce pseudo-random values.
file	AlgRandZig.c
	The Gaussian distribution random number generator is based on the Ziggurat method for generating random variables as used in the GNU scientific library. For details of the Ziggurat method see: George Marsaglia, Wai Wan Tsang The Ziggurat Method for Generating Random Variables, Journal of Statistical Software, vol. 5 (2000), no. 8 (http://www.jstatsoft.org/v05/i08/).
file	AlgShuffle.c
	Functions for randomly permuting data.

Functions
void	AlgRandSeed (long seed)
	Seeds the pseudo-random number generators. More...
double	AlgRandUniform (void)
	Produces a pseudo-random value from a uniform distribution over the interval [0.0, 1.0]. More...
double	AlgRandNormal (double mu, double sigma)
	Produces a pseudo-random value from a normal distribution over the interval [-1.0, 1.0]. More...
double	AlgRandZigNormal (double mu, double sigma)
	Generates a random double from a gaussian distribution the Ziggurat method. The distribution generated by this function is not quite as smooth as that generated by AlgRandNormal() but the time taken is a factor of ten smaller. More...
AlgError	AlgShuffleIdx (int nShuffle, int *shuffle, int seed)
	Inserts indicies into the given array which can be used to shuffle data. The permuted indicies are in the range [0-(nShuffle-1)] with a random order. This shuffling algorithm is based on a published paper! Dursenfeld R. "Random Permutation" CACM July 1964 No 7 p420. More...

Detailed Description

Function Documentation

AlgRandSeed()

void AlgRandSeed

(

long

seed

)

Seeds the pseudo-random number generators.

Returns

void

Parameters

seed	Given seed value.

Referenced by WlzBasisFnTransformRandom(), WlzGaussNoise(), and WlzGreySetRange().

AlgRandUniform()

double AlgRandUniform

(

void

)

Produces a pseudo-random value from a uniform distribution over the interval [0.0, 1.0].

Returns

Pseudo-random value.

Referenced by AlgRandNormal(), AlgRandZigNormal(), WlzBasisFnTransformRandom(), WlzPointsDither(), WlzPointsFromDomObj(), and WlzValueDitherI().

AlgRandNormal()

double AlgRandNormal	(	double	mu,
		double	sigma
	)

Produces a pseudo-random value from a normal distribution over the interval [-1.0, 1.0].

Returns

Pseudo-random value.

Parameters

mu	Mean of distribution.
sigma	Standard deviation of distribution.

References AlgRandUniform().

Referenced by WlzGaussNoise().

AlgRandZigNormal()

double AlgRandZigNormal	(	double	mu,
		double	sigma
	)

Generates a random double from a gaussian distribution the Ziggurat method. The distribution generated by this function is not quite as smooth as that generated by AlgRandNormal() but the time taken is a factor of ten smaller.

Returns

Random double from gaussian distribution.

Parameters

mu	Mean of distribution.
sigma	Standard deviation of distribution.

References AlgRandUniform().

Referenced by WlzGreySetRange().

AlgShuffleIdx()

AlgError AlgShuffleIdx	(	int	nShuffle,
		int *	shuffle,
		int	seed
	)

Inserts indicies into the given array which can be used to shuffle data. The permuted indicies are in the range [0-(nShuffle-1)] with a random order. This shuffling algorithm is based on a published paper! Dursenfeld R. "Random Permutation" CACM July 1964 No 7 p420.

Returns

Error code.

Parameters

nShuffle	Number of permuted indicies to insert into in shuffle.
shuffle	Array into which shuffled indicies are placed.
seed	Seed fro random permutation.

References ALG_ERR_FUNC, and ALG_ERR_NONE.

Referenced by WlzBasisFnTransformRandom(), WlzPointsFromDomObj(), WlzSnapFit(), and WlzVerticesBuildTree().