function sinc( x ) {
	return addon( x );
}
Computes the normalized cardinal sine of a number.

@private
@param {number} x - input value
@returns {number} cardinal sine

@example
var v = sinc( 0.5 );
// returns ~0.637

@example
var v = sinc( -1.2 );
// returns ~-0.156

@example
var v = sinc( 0.0 );
// returns 1.0

@example
var v = sinc( NaN );
// returns NaN