function quantile( p, mu, s ) {
	if (
		isnan( mu ) ||
		isnan( s ) ||
		isnan( p ) ||
		s < 0.0 ||
		p < 0.0 ||
		p > 1.0
	) {
		return NaN;
	}
	if ( s === 0.0 ) {
		return mu;
	}
	return mu + ( s * ln( p / ( 1.0-p ) ) );
}
Evaluates the quantile function for a logistic distribution with location parameter `mu` and scale parameter `s` at a probability `p`.

@param {Probability} p - input value
@param {number} mu - location parameter
@param {NonNegativeNumber} s - scale parameter
@returns {number} evaluated quantile function

@example
var y = quantile( 0.8, 0.0, 1.0 );
// returns ~1.386

@example
var y = quantile( 0.5, 4.0, 2.0 );
// returns 4.0

@example
var y = quantile( 1.1, 0.0, 1.0 );
// returns NaN

@example
var y = quantile( -0.2, 0.0, 1.0 );
// returns NaN

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

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

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

@example
// Negative scale parameter:
var y = quantile( 0.5, 0.0, -1.0 );
// returns NaN