poisslike
              Negative log-likelihood for the Poisson distribution.
 nlogL = poisslike (lambda, x) returns the negative
 log likelihood of the data in x corresponding to the Poisson
 distribution with rate parameter lambda.  x must be a vector of
 non-negative values.
 [nlogL, avar] = poisslike (lambda, x) also
 returns the inverse of Fisher’s information matrix, avar.  If the input
 rate parameter, lambda, is the maximum likelihood estimate, avar
 is its asymptotic variance.
 […] = poisslike (lambda, x, freq) accepts a
 frequency vector, freq, of the same size as x.  freq
 typically contains integer frequencies for the corresponding elements in
 x, but it can contain any non-integer non-negative values.  By default,
 or if left empty, freq = ones (size (x)).
Further information about the Poisson distribution can be found at https://en.wikipedia.org/wiki/Poisson_distribution
See also: poisscdf, poissinv, poisspdf, poissrnd, poissfit, poisstat
Source Code: poisslike