function mgf( t, mu, s ) {
	var st;
	st = s * t;
	if (
		isnan( st ) ||
		isnan( mu ) ||
		s < 0.0 ||
		abs( st ) > 1.0
	) {
		return NaN;
	}
	return exp( mu * t ) / sinc( st );
}
Evaluates the moment-generating function (MGF) for a logistic distribution with mean `mu` and scale parameter `s` at a value `t`.

@param {number} t - input value
@param {number} mu - mean
@param {NonNegativeNumber} s - scale parameter
@returns {number} evaluated MGF

@example
var y = mgf( 0.9, 0.0, 1.0 );
// returns ~9.15

@example
var y = mgf( 0.1, 4.0, 4.0 );
// returns ~1.971

@example
var y = mgf( -0.2, 4.0, 4.0 );
// returns ~1.921

@example
var y = mgf( 0.5, 0.0, -1.0 );
// returns NaN

@example
var y = mgf( 0.5, 0.0, 4.0 );
// returns NaN

@example
var y = mgf( NaN, 0.0, 1.0 );
// returns NaN

@example
var y = mgf( 0.0, NaN, 1.0 );
// returns NaN

@example
var y = mgf( 0.0, 0.0, NaN );
// returns NaN