docs: public static double logpdf(double x, double mu, double shape) {
      if(!(x > 0) || x == Double.POSITIVE_INFINITY) {
        return x == x ? Double.NEGATIVE_INFINITY : Double.NaN;
      }
      final double v = (x - mu) / mu;
      return v < Double.MAX_VALUE ? 0.5 * FastMath.log(shape / (MathUtil.TWOPI * x * x * x)) - shape * v * v / (2. * x) : Double.NEGATIVE_INFINITY;
    }