function factory( mu ) {
	if ( isnan( mu ) ) {
		return constantFunction( NaN );
	}
	return mgf;

	/**
	* Evaluates the moment-generating function (MGF) of a degenerate distribution.
	*
	* @private
	* @param {number} t - input value
	* @returns {number} evaluated MGF
	*
	* @example
	* var y = mgf( 10.0 );
	* // returns <number>
	*/
	function mgf( t ) {
		if ( isnan( t ) ) {
			return NaN;
		}
		return exp( mu*t );
	}
}
Returns a function for evaluating the moment-generating function (MGF) of a degenerate distribution centered at a provided mean value.

@param {number} mu - value at which to center the distribution
@returns {Function} MGF

@example
var mgf = factory( 2.0 );

var y = mgf( 0.0 );
// returns 1.0

y = mgf( 2.0 );
// returns ~54.598