还是给你回答了吧
parmhat = gpfit(X) 产生pareto随机数
参数估计,
[parmhat,parmci] = gpfit(X)
参数估计,有alpha
[parmhat,parmci] = gpfit(X,alpha)
GPFIT Parameter estimates and confidence intervals for generalized Pareto data.
PARMHAT = GPFIT(X) returns maximum likelihood estimates of the parameters
of the two-parameter generalized Pareto (GP) distribution given the data
in X. PARMHAT(1) is the tail index (shape) parameter, K and PARMHAT(2) is
the scale parameter, SIGMA. GPFIT does not fit a threshold (location)
parameter.
[PARMHAT,PARMCI] = GPFIT(X) returns 95% confidence intervals for the
parameter estimates.
[PARMHAT,PARMCI] = GPFIT(X,ALPHA) returns 100(1-ALPHA) percent confidence
intervals for the parameter estimates.
[...] = GPFIT(X,ALPHA,OPTIONS) specifies control parameters for the
iterative algorithm used to compute ML estimates. This argument can be
created by a call to STATSET. See STATSET('gpfit') for parameter names
and default values.
Pass in [] for ALPHA to use the default values.
Other functions for the generalized Pareto, such as GPCDF, allow a
threshold parameter THETA. However, GPFIT does not estimate THETA, and it
must be assumed known, and subtracted from X before calling GPFIT.
When K = 0 and THETA = 0, the GP is equivalent to the exponential
distribution. When K > 0 and THETA = SIGMA, the GP is equivalent to the
Pareto distribution. The mean of the GP is not finite when K >= 1, and the
variance is not finite when K >= 1/2. When K >= 0, the GP has positive
density for X>THETA, or, when K < 0, for 0 <= (X-THETA)/SIGMA <= -1/K.