RandomVariable

Random number generator

SYNOPSIS

include "dip_noise.h"

dip_Error dip_RandomVariable ( random, value )

FUNCTION

Generates a random number between zero and one. The dip_Random structure must be initialized with the function RandomSeed. If the supplied dip_Random structure is not initialized, RandomVariable will initialize the dip_Random structure with the default seed. To guarantee the (psuedo) randomness between variables obtained with subsequent calls to RandomVariable (or to functions that use this function to obtain a random variable), a pointer to the same dip_Random structure has to supplied when calling RandomVariable.

The random number generator returns random numbers as 32-bit integers, which are normalised to to [0,1] range. If higher precision numbers are required, you can set random.highprecision to DIP_TRUE. This causes two random 32-bit values to be used for each floating point output value, doubling the precision of the output. There is no need to re-initialise the random structure after changing this setting.

This function is based on LGPL code by Geoff Kuenning (mtwist-0.8) implementing the Mersenne Twister pseudo-random number generator.

ARGUMENTS

Data type	Name	Description
`dip_Random *`	`random`	Pointer to a random value structure
`dip_float *`	`value`	Random value

EXAMPLE

Obtain a random number as follows:

   dip_Random random;
   dip_float val;

   DIPXJ( dip_RandomSeed( &random, 0 ));
   DIPXJ( dip_RandomVariable( &random, &val ));

LITERATURE