Compute mean and variance of the exponential distribution.
Arguments
-  l is the parameter of the exponential distribution. The
elements of l must be positive
Return values
-  m is the mean of the exponential distribution
-  v is the variance of the exponential distribution
Example
l = 1:6;
[m, v] = expstat (l)
 
References
-  Wendy L. Martinez and Angel R. Martinez. Computational Statistics
Handbook with MATLAB. Appendix E, pages 547-557, Chapman & Hall/CRC,
2001.
-  Athanasios Papoulis. Probability, Random Variables, and Stochastic
Processes. McGraw-Hill, New York, second edition, 1984.
See also: expcdf, expfit, expinv, explike, exppdf, exprnd.