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iterNegaLucasSeq

Create an iterator which generates a negaLucas sequence.

The negaLucas 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

$$L_{n-2} = L_{n} - L_{n-1}$$

which yields

$$L_{-n} = (-1)^{n} L_n$$

with seed values L_0 = 2 and L_{-1} = -1.

Installation

npm install @stdlib/math-iter-sequences-negalucas

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var iterNegaLucasSeq = require( '@stdlib/math-iter-sequences-negalucas' );

iterNegaLucasSeq( [options] )

Returns an iterator which generates a negaLucas sequence.

var it = iterNegaLucasSeq();
// 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 negaLucas numbers, as larger negaLucas 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 = iterNegaLucasSeq( 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 iterNegaLucasSeq = require( '@stdlib/math-iter-sequences-negalucas' );

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

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

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See Also

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

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Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.