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GwyRandGenSet represents a set of pseudoradnom number generators initialised together, but each producing a different sequence of numbers. This is useful when you use pseudorandom number generators to optionally randomize several different things. Using a common generator would require always generating exactly the same number of random numbers, even for quantities you do not want randomized, in order to keep the random number sequences stable.
GwyRandGenSet also provides functions sample a few common distributions such as Gaussian or exponential. It should be noted that the individual sampling functions may advance the generator state differently. This means
1 2 |
x = gwy_rand_gen_set_gaussian(rngset, 0, 1.0); y = gwy_rand_gen_set_gaussian(rngset, 0, 1.0); |
may produce a different value of y
than
1 2 |
x = gwy_rand_gen_set_exponential(rngset, 0, 1.0); y = gwy_rand_gen_set_gaussian(rngset, 0, 1.0); |
even if the initial generator state was the same.
GwyRandGenSet *
gwy_rand_gen_set_new (guint n);
Creates a new set of pseudorandom number generators.
The generators are initialised to random states.
Since: 2.37
void gwy_rand_gen_set_init (GwyRandGenSet *rngset,guint seed);
Initialises a set of pseudorandom number generators using an integer seed.
rngset |
A set of pseudorandom number generators. |
|
seed |
The seed used to initialise the generators. |
Since: 2.37
void
gwy_rand_gen_set_free (GwyRandGenSet *rngset);
Destroys a set of pseudorandom number generators.
If you obtained individual generators using gwy_rand_gen_get_rng() you may
not use them any more after calling this function.
Since: 2.37
GRand * gwy_rand_gen_set_rng (GwyRandGenSet *rngset,guint i);
Obtains a single generator from a set of pseudorandom number generators.
The generator can be used to produce random numbers in any way for which you find the provided methods insufficient. However, if you reseed it manually, number sequence stability will be broken because sampling functions may keep persistent information between calls.
Since: 2.37
gdouble gwy_rand_gen_set_range (GwyRandGenSet *rngset,guint i,gdouble lower,gdouble upper);
Samples from a uniform distribution over given interval using one generator from a pseudorandom number generator set.
The generated number always lies inside the interval, neither endpoint value
is ever returned. Note if there are no representable real numbers between
lower
and upper
this function will never terminate. You must ensure
upper
is sufficiently larger than lower
.
rngset |
A set of pseudorandom number generators. |
|
i |
Index of a generator from the set. |
|
lower |
Lower limit of the range. |
|
upper |
Upper limit of the range. |
Since: 2.37
gdouble gwy_rand_gen_set_uniform (GwyRandGenSet *rngset,guint i,gdouble sigma);
Samples from a centered uniform distribution using one generator from a pseudorandom number generator set.
The mean value of the distribution is zero, the rms value is given by
sigma
.
rngset |
A set of pseudorandom number generators. |
|
i |
Index of a generator from the set. |
|
sigma |
Rms of the distribution. |
Since: 2.37
gdouble gwy_rand_gen_set_gaussian (GwyRandGenSet *rngset,guint i,gdouble sigma);
Samples from a centered Gaussian distribution using one generator from a pseudorandom number generator set.
The mean value of the distribution is zero, the rms value is given by
sigma
.
rngset |
A set of pseudorandom number generators. |
|
i |
Index of a generator from the set. |
|
sigma |
Rms of the distribution. |
Since: 2.37
gdouble gwy_rand_gen_set_exponential (GwyRandGenSet *rngset,guint i,gdouble sigma);
Samples from a centered exponential distribution using one generator from a pseudorandom number generator set.
The mean value of the distribution is zero, the rms value is given by
sigma
.
rngset |
A set of pseudorandom number generators. |
|
i |
Index of a generator from the set. |
|
sigma |
Rms of the distribution. |
Since: 2.37
gdouble gwy_rand_gen_set_triangular (GwyRandGenSet *rngset,guint i,gdouble sigma);
Samples from a centered triangular distribution using one generator from a pseudorandom number generator set.
The mean value of the distribution is zero, the rms value is given by
sigma
.
rngset |
A set of pseudorandom number generators. |
|
i |
Index of a generator from the set. |
|
sigma |
Rms of the distribution. |
Since: 2.37
gdouble gwy_rand_gen_set_multiplier (GwyRandGenSet *rngset,guint i,gdouble range);
Samples from a multiplier distribution using one generator from a pseudorandom number generator set.
The multiplier distribution is triangular distribution centered at 1,
with values from [1-range
, 1+range
].
rngset |
A set of pseudorandom number generators. |
|
i |
Index of a generator from the set. |
|
sigma |
Rms of the distribution. |
Since: 2.37
gdouble gwy_rand_gen_set_double (GwyRandGenSet *rngset,guint i);
Samples uniform distribution over [0,1) using one generator from a pseudorandom number generator set.
rngset |
A set of pseudorandom number generators. |
|
i |
Index of a generator from the set. |
|
sigma |
Rms of the distribution. |
Since: 2.37
guint32 gwy_rand_gen_set_int (GwyRandGenSet *rngset,guint i);
Samples a 32bit integer using a generator from a pseudorandom number generator set.
Since: 2.37
typedef struct _GwyRandGenSet GwyRandGenSet;
GwyRandGenSet is an opaque data structure and should be only manipulated with the functions below.
Since: 2.37