code: function quantile( p, mu, sigma ) {
  	if ( p !== p || p < 0 || p > 1 ) {
  		return NaN;
  	}
  	return exp( mu + sigma * qnormal( p ) );
  }
docs: QUANTILE // 
  FUNCTION: quantile( p, mu, sigma )
  Evaluates the quantile function for a Lognormal distribution with location parameter `mu` and scale parameter `sigma` at a probability `p`.
  
  @param {Number} p - input value
  @param {Number} mu - location parameter
  @param {Number} sigma - scale parameter
  @returns {Number} evaluated quantile function