negaFibonacci

Compute the nth negaFibonacci number.

The negaFibonacci numbers are the integer sequence

0 comma 1 comma negative 1 comma 2 comma negative 3 comma 5 comma negative 8 comma 13 comma negative 21 comma 34 comma negative 55 comma 89 comma negative 144 comma ellipsis

The sequence is defined by the recurrence relation

upper F Subscript n minus 2 Baseline equals upper F Subscript n Baseline minus upper F Subscript n minus 1

which yields

upper F Subscript negative n Baseline equals left-parenthesis negative 1 right-parenthesis Superscript n plus 1 Baseline upper F Subscript n

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

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 );
}