function mgf( t ) {
		if ( isnan( t ) || t >= lambda ) {
			return NaN;
		}
		return pow( 1.0 - (t/lambda), -k );
	}
Evaluates the moment-generating function (MGF) for an Erlang distribution.

@private
@param {number} t - input value
@returns {number} evaluated MGF

@example
var y = mgf( 0.5 );
// returns <number>