iterLucasSeq

Create an iterator which generates a Lucas sequence.

The Lucas numbers are the integer sequence

$$2, 1, 3, 4, 7, 11, 18, 29, 47, 76, 123, 199, 322, \ldots$$

The sequence is defined by the recurrence relation

$$L_n = \begin{cases}2 & \textrm{if}\ n = 0\\1 & \textrm{if}\ n = 1\\L_{n-1} + L_{n-2} & \textrm{if}\ n > 1\end{cases}$$

Usage

var iterLucasSeq = require( '@stdlib/math/iter/sequences/lucas' );

iterLucasSeq( [options] )

Returns an iterator which generates a Lucas sequence.

var it = iterLucasSeq();
// returns <Object>

var v = it.next().value;
// returns 2

v = it.next().value;
// returns 1

v = it.next().value;
// returns 3

// ...

The returned iterator protocol-compliant object has the following properties:

• next: function which returns an iterator protocol-compliant object containing the next iterated value (if one exists) assigned to a value property and a done property having a boolean value indicating whether the iterator is finished.
• return: function which closes an iterator and returns a single (optional) argument in an iterator protocol-compliant object.

The function supports the following options:

• iter: number of iterations. Default: 77.

The returned iterator can only generate the first 77 Lucas numbers, as larger Lucas numbers cannot be safely represented in double-precision floating-point format. By default, the function returns an iterator which generates all 77 numbers. To limit the number of iterations, set the iter option.

var opts = {
    'iter': 2
};
var it = iterLucasSeq( opts );
// returns <Object>

var v = it.next().value;
// returns 2

v = it.next().value;
// returns 1

var bool = it.next().done;
// returns true

Notes

• If an environment supports Symbol.iterator, the returned iterator is iterable.

Examples

var iterLucasSeq = require( '@stdlib/math/iter/sequences/lucas' );

// Create an iterator:
var it = iterLucasSeq();

// Perform manual iteration...
var v;
while ( true ) {
    v = it.next();
    if ( v.done ) {
        break;
    }
    console.log( v.value );
}

---

See Also

• @stdlib/math/base/special/lucas: compute the nth Lucas number.
• @stdlib/math/iter/sequences/fibonacci: create an iterator which generates a Fibonacci sequence.
• @stdlib/math/iter/sequences/negalucas: create an iterator which generates a negaLucas sequence.