Triangular Random Numbers

Usage

var triangular = require( '@stdlib/random/base/triangular' );

triangular( a, b, c )

Returns a pseudorandom number drawn from a triangular distribution with parameters a (minimum support), b (maximum support), and c (mode).

var r = triangular( 2.0, 5.0, 3.33 );
// returns <number>

If either a, b, or c is NaN, the function returns NaN.

var r = triangular( NaN, 1.0, 0.5 );
// returns NaN

r = triangular( 1.0, NaN, 2.42 );
// returns NaN

r = triangular( 1.0, 10.0, NaN );
// returns NaN

If the condition a <= c <= b is not satisfied, the function returns NaN.

var r = triangular( 13.0, 9.0, 0.5 );
// returns NaN

triangular.factory( [a, b, c, ][options] )

Returns a pseudorandom number generator (PRNG) for generating pseudorandom numbers drawn from a triangular distribution.

var rand = triangular.factory();

var r = rand( 0.0, 1.0, 0.5 );
// returns <number>

If provided a, b, and c, the returned generator returns random variates from the specified distribution.

var rand = triangular.factory( -2.0, 2.0, 1.0 );

var r = rand();
// returns <number>

r = rand();
// returns <number>

If not provided a, b, and c, the returned generator requires that all three parameters be provided at each invocation.

var rand = triangular.factory();

var r = rand( 0.0, 1.0, 0.75 );
// returns <number>

r = rand( -2.0, 2.0, 0.1 );
// returns <number>

The function accepts the following options:

• prng: pseudorandom number generator for generating uniformly distributed pseudorandom numbers on the interval [0,1). If provided, the function ignores both the state and seed options. In order to seed the returned pseudorandom number generator, one must seed the provided prng (assuming the provided prng is seedable).
• seed: pseudorandom number generator seed.
• state: a Uint32Array containing pseudorandom number generator state. If provided, the function ignores the seed option.
• copy: boolean indicating whether to copy a provided pseudorandom number generator state. Setting this option to false allows sharing state between two or more pseudorandom number generators. Setting this option to true ensures that a returned generator has exclusive control over its internal state. Default: true.

To use a custom PRNG as the underlying source of uniformly distributed pseudorandom numbers, set the prng option.

var minstd = require( '@stdlib/random/base/minstd' );

var rand = triangular.factory({
    'prng': minstd.normalized
});

var r = rand( 2.0, 4.0, 3.0 );
// returns <number>

To seed a pseudorandom number generator, set the seed option.

var rand1 = triangular.factory({
    'seed': 12345
});

var r1 = rand1( 2.0, 4.0, 3.0 );
// returns <number>

var rand2 = triangular.factory( 2.0, 4.0, 3.0, {
    'seed': 12345
});

var r2 = rand2();
// returns <number>

var bool = ( r1 === r2 );
// returns true

To return a generator having a specific initial state, set the generator state option.

var rand;
var bool;
var r;
var i;

// Generate pseudorandom numbers, thus progressing the generator state:
for ( i = 0; i < 1000; i++ ) {
    r = triangular( 0.0, 1.0, 0.5 );
}

// Create a new PRNG initialized to the current state of `triangular`:
rand = triangular.factory({
    'state': triangular.state
});

// Test that the generated pseudorandom numbers are the same:
bool = ( rand( 0.0, 1.0, 0.5 ) === triangular( 0.0, 1.0, 0.5 ) );
// returns true

triangular.NAME

The generator name.

var str = triangular.NAME;
// returns 'triangular'

triangular.PRNG

The underlying pseudorandom number generator.

var prng = triangular.PRNG;
// returns <Function>

triangular.seed

The value used to seed triangular().

var rand;
var r;
var i;

// Generate pseudorandom values...
for ( i = 0; i < 100; i++ ) {
    r = triangular( 0.0, 10.0, 3.0 );
}

// Generate the same pseudorandom values...
rand = triangular.factory( 0.0, 10.0, 3.0, {
    'seed': triangular.seed
});
for ( i = 0; i < 100; i++ ) {
    r = rand();
}

If provided a PRNG for uniformly distributed numbers, this value is null.

var rand = triangular.factory({
    'prng': Math.random
});

var seed = rand.seed;
// returns null

triangular.seedLength

Length of generator seed.

var len = triangular.seedLength;
// returns <number>

If provided a PRNG for uniformly distributed numbers, this value is null.

var rand = triangular.factory({
    'prng': Math.random
});

var len = rand.seedLength;
// returns null

triangular.state

Writable property for getting and setting the generator state.

var r = triangular( 0.0, 1.0, 0.5 );
// returns <number>

r = triangular( 0.0, 1.0, 0.5 );
// returns <number>

// ...

// Get a copy of the current state:
var state = triangular.state;
// returns <Uint32Array>

r = triangular( 0.0, 1.0, 0.5 );
// returns <number>

r = triangular( 0.0, 1.0, 0.5 );
// returns <number>

// Reset the state:
triangular.state = state;

// Replay the last two pseudorandom numbers:
r = triangular( 0.0, 1.0, 0.5 );
// returns <number>

r = triangular( 0.0, 1.0, 0.5 );
// returns <number>

// ...

If provided a PRNG for uniformly distributed numbers, this value is null.

var rand = triangular.factory({
    'prng': Math.random
});

var state = rand.state;
// returns null

triangular.stateLength

Length of generator state.

var len = triangular.stateLength;
// returns <number>

If provided a PRNG for uniformly distributed numbers, this value is null.

var rand = triangular.factory({
    'prng': Math.random
});

var len = rand.stateLength;
// returns null

triangular.byteLength

Size (in bytes) of generator state.

var sz = triangular.byteLength;
// returns <number>

If provided a PRNG for uniformly distributed numbers, this value is null.

var rand = triangular.factory({
    'prng': Math.random
});

var sz = rand.byteLength;
// returns null

triangular.toJSON()

Serializes the pseudorandom number generator as a JSON object.

var o = triangular.toJSON();
// returns { 'type': 'PRNG', 'name': '...', 'state': {...}, 'params': [] }

If provided a PRNG for uniformly distributed numbers, this method returns null.

var rand = triangular.factory({
    'prng': Math.random
});

var o = rand.toJSON();
// returns null