

   TThhee EExxppoonneennttiiaall DDiissttrriibbuuttiioonn

        dexp(x, rate = 1)
        pexp(q, rate = 1)
        qexp(p, rate = 1)
        rexp(n, rate = 1)

   AArrgguummeennttss::

        x q: vector of quantiles

          p: vector of probabilities

          n: number of observations to generate

       rate: vector of rates

   VVaalluuee::

        These functions provide information about the exponen-
        tial distribution with rate `rate' (i.e., mean
        `1/rate').  `dexp' gives the density, `pexp' gives the
        distribution function, `qexp' gives the quantile func-
        tion and `rexp' generates random deviates.

        The exponential distribution with rate lambda has den-
        sity

                     f(x) = lambda e^(- lambda x)

        for x >= 0.

   SSeeee AAllssoo::

        `exp', `dchisq' for the chisquare and `dweibull' for
        the Weibull distribution which both generalize the
        exponential.

   EExxaammpplleess::

        dexp(1) - exp(-1) #-> 0
        r <- rexp(100)
        all(abs(1 - dexp(1, r) / (r*exp(-r))) < 1e-14)

