function binomcoef( n, k ) {
	return addon( n, k );
}
Computes the binomial coefficient of two integers.

@private
@param {integer} n - input value
@param {integer} k - second input value
@returns {number} function value

@example
var v = binomcoef( 8, 2 );
// returns 28.0

@example
var v = binomcoef( 0, 0 );
// returns 1.0

@example
var v = binomcoef( -4, 2 );
// returns 10.0