var gammaDist = function(){
  
  var gamma = {},
      shape, 
      scale;
  
  var labeler = function(shape, scale){
    return "Gamma(α = " + d3.round(shape, 3) + ", " + 
      			     "θ = " + d3.round(scale, 3) + ")";
  }
  
  gamma.shape = function(_) {
    if (!arguments.length) return shape;
    shape = _;
    gamma.label = labeler(shape, scale);
    return gamma;
  };

  gamma.scale = function(_) {
    if (!arguments.length) return scale;
    scale = _;
    gamma.label = labeler(shape, scale);
    return gamma;
  };

  gamma.mean = function(_) {
    if (!arguments.length) return jStat.gamma.mean(shape, scale);
    scale = _ / shape;
    gamma.label = labeler(shape, scale);
    return gamma;
  };

  gamma.pdf = function(x){ return jStat.gamma.pdf(x, shape, scale); }      
  gamma.cdf = function(x){ return jStat.gamma.cdf(x, shape, scale); }
  gamma.inv = function(p){ return jStat.gamma.inv(p, shape, scale); }
  
  return gamma;
}

var lognormalDist = function(){
  
  var lognormal = {},
      mu, 
      sigma;
  
  var labeler = function(mu, sigma){
    return "Lognormal(μ = " + d3.round(mu, 3) + ", " + 
    								 "σ = " + d3.round(sigma, 3) + ")";
  }
  
  lognormal.mu = function(_) {
    if (!arguments.length) return mu;
    mu = _;
    lognormal.label = labeler(mu, sigma);
    return lognormal;
  };

  lognormal.sigma = function(_) {
    if (!arguments.length) return sigma;
    sigma = _;
    lognormal.label = labeler(mu, sigma);
    return lognormal;
  };

  lognormal.mean = function(_) {
    if (!arguments.length) return jStat.lognormal.mean(mu, sigma);
    mu = Math.log(_) - (sigma * sigma) / 2;
    lognormal.label = labeler(mu, sigma);
    return lognormal;
  };

  lognormal.pdf = function(x){ return jStat.lognormal.pdf(x, mu, sigma); }      
  lognormal.cdf = function(x){ return jStat.lognormal.cdf(x, mu, sigma); }
  lognormal.inv = function(p){ return jStat.lognormal.inv(p, mu, sigma); }
  
  return lognormal;
}


var paretoDist = function(){
  
  var pareto = {}, 
      scale,
      shape;
  
  var labeler = function(scale, shape){
    return "Pareto(x_m = " + d3.round(scale, 3) + ", " + 
    			 "α = " + d3.round(shape, 3) + ")";
  }
  
  pareto.shape = function(_) {
    if (!arguments.length) return shape;
    shape = _;
    pareto.label = labeler(scale, shape);
    return pareto;
  };

  pareto.scale = function(_) {
    if (!arguments.length) return scale;
    scale = _;
    pareto.label = labeler(scale, shape);
    return pareto;
  };

  pareto.mean = function(_) {
    if (!arguments.length) return jStat.pareto.mean(scale, shape);
    scale = _  * (shape - 1) / shape;
    pareto.label = labeler(scale, shape);
    return pareto;
  };

  pareto.pdf = function(x){ return jStat.pareto.pdf(x, scale, shape); }      
  pareto.cdf = function(x){ return jStat.pareto.cdf(x, scale, shape); }
  pareto.inv = function(p){ return jStat.pareto.inv(p, scale, shape); }
  
  return pareto;
}

var weibullDist = function(){
  
  var weibull = {}, 
      scale,
      shape;
  
  var labeler = function(scale, shape){
    return "Weibull(λ = " + d3.round(scale, 3) + ", " + 
    							 "k = " + d3.round(shape, 3) + ")";
  }
  
  weibull.shape = function(_) {
    if (!arguments.length) return shape;
    shape = _;
    weibull.label = labeler(scale, shape);
    return weibull;
  };

  weibull.scale = function(_) {
    if (!arguments.length) return scale;
    scale = _;
    weibull.label = labeler(scale, shape);
    return weibull;
  };

  weibull.mean = function(_) {
    if (!arguments.length) return jStat.weibull.mean(scale, shape);
    scale = _ / jStat.gammafn(1 + 1/shape);
    weibull.label = labeler(scale, shape);
    return weibull;
  };

  weibull.pdf = function(x){ return jStat.weibull.pdf(x, scale, shape); }      
  weibull.cdf = function(x){ return jStat.weibull.cdf(x, scale, shape); }
  weibull.inv = function(p){ return jStat.weibull.inv(p, scale, shape); }
  
  return weibull;
}