hnlike
              Negative log-likelihood for the half-normal distribution.
 nlogL = hnlike (params, x) returns the negative
 log likelihood of the data in x corresponding to the half-normal
 distribution with (1) location parameter mu and (2) scale parameter
 sigma given in the two-element vector params.
 [nlogL, acov] = hnlike (params, x) returns
 the inverse of Fisher’s information matrix, acov.  If the input
 parameter values in params are the maximum likelihood estimates, the
 diagonal elements of params are their asymptotic variances.
 The half-normal CDF is only defined for x >= mu.
Further information about the half-normal distribution can be found at https://en.wikipedia.org/wiki/Half-normal_distribution
See also: hncdf, hninv, hnpdf, hnrnd, hnfit
Source Code: hnlike