negaLucas

Compute the nth negaLucas number.

The negaLucas numbers are the integer sequence

2 comma negative 1 comma 3 comma negative 4 comma 7 comma negative 11 comma 18 comma negative 29 comma 47 comma negative 76 comma 123 comma negative 199 comma 322 comma ellipsis

The sequence is defined by the recurrence relation

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

which yields

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

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

Usage

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

negalucas( n )

Computes the nth negaLucas number.

var v = negalucas( 0 );
// returns 2

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

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

v = negalucas( -3 );
// returns -4

v = negalucas( -76 );
// returns 7639424778862807

If n < -76, the function returns NaN, as larger negaLucas numbers cannot be safely represented in double-precision floating-point format.

var v = negalucas( -77 );
// returns NaN

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

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

v = negalucas( 1 );
// returns NaN

If provided NaN, the function returns NaN.

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

Examples

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

var v;
var i;

for ( i = 0; i > -77; i-- ) {
    v = negalucas( i );
    console.log( v );
}