/// <summary>
/// Get the mean and variance
/// </summary>
/// <param name="mean">Where to put the mean</param>
/// <param name="variance">Where to put the variance</param>
public void GetMeanAndVariance(out double mean, out double variance)
{
if (Power == 0)
{
mean = 1;
variance = 0;
}
if (IsPointMass)
{
mean = Point;
variance = 0;
}
else if (!IsProper() && Rate != 0)
{
throw new ImproperDistributionException(this);
}
else
{
double logMean = GetLogMeanPower(1);
mean = Math.Exp(logMean);
if (Rate == 0 && Shape + 2 * Power == 0 && 2 * Power < -1)
{
variance = 0;
}
else if (Shape + 2 * Power <= 0)
{
variance = double.PositiveInfinity;
}
else
{
double logMean2 = GetLogMeanPower(2);
if (logMean2 > double.MaxValue)
{
variance = double.PositiveInfinity;
}
else
{
variance = MMath.DifferenceOfExp(logMean2, 2 * logMean);
}
}
}
}