nodejs javascript stdlib node node-js mathematics math special-functions special function fibonacci negafibonacci fib nfib number

negaFibonacci

$Build Status$

Compute the nth negaFibonacci number.

The negaFibonacci numbers are the integer sequence

$$0, 1, -1, 2, -3, 5, -8, 13, -21, 34, -55, 89, -144, \ldots$$

The sequence is defined by the recurrence relation

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

which yields

$$F_{-n} = (-1)^{n+1} F_n$$

with seed values F_0 = 0 and F_{-1} = 1.

Installation

npm install @stdlib/math-base-special-negafibonacci

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.
If you are using Deno, visit the deno branch.
For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch.

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

Usage

var negafibonacci = require( '@stdlib/math-base-special-negafibonacci' );

negafibonacci( n )

Computes the nth negaFibonacci number.

var v = negafibonacci( 0 );
// returns 0

v = negafibonacci( -1 );
// returns 1

v = negafibonacci( -2 );
// returns -1

v = negafibonacci( -3 );
// returns 2

v = negafibonacci( -78 );
// returns -8944394323791464

If n < -78, the function returns NaN, as larger negaFibonacci numbers cannot be safely represented in double-precision floating-point format.

var v = negafibonacci( -79 );
// returns NaN

If not provided a nonpositive integer value, the function returns NaN.

var v = negafibonacci( -3.14 );
// returns NaN

v = negafibonacci( 1 );
// returns NaN

If provided NaN, the function returns NaN.

var v = negafibonacci( NaN );
// returns NaN

Examples

var negafibonacci = require( '@stdlib/math-base-special-negafibonacci' );

var v;
var i;

for ( i = 0; i > -79; i-- ) {
    v = negafibonacci( i );
    console.log( v );
}

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.