Type-2 Gumbel distribution
This implies that it is similar to the Weibull distributions, substituting and . Note however that a positive k (as in the Weibull distribution) would yield a negative a, which is not allowed here as it would yield a negative probability density.
The moments exist for
The special case b = 1 yields the Fréchet distribution
Based on The GNU Scientific Library, used under GFDL.