

   LLooggaarriitthhmmss aanndd EExxppoonneennttiiaallss

        log(x)
        log(x, base)
        log10(x)
        log2(x)
        exp(x)

   AArrgguummeennttss::

          x: a numeric or complex vector.

       base: positive number. The base with respect to which
             logarithms are computed.  Defaults to e=`exp(1)'.

   DDeessccrriippttiioonn::

        `log' computes natural logarithms, `log10' computes
        common (i.e., base 10) logarithms, and `log2' computes
        binary (i.e., base 2) logarithms.  The general form
        `log(x, base)' computes logarithms with base `base'
        (`log10' and `log2' are only special cases).

        `exp' computes the exponential function.

   VVaalluuee::

        A vector of the same length as `x' containing the
        transformed values.

   SSeeee AAllssoo::

        `Trig', `Math', `Arithmetic'.

   EExxaammpplleess::

        log(exp(3))
        all(log(1:10) ==log(1:10, exp(1)))
        log10(30) == log(30, 10)
        log10(1e7)# = 7
        log2(2^pi) == 2^log2(pi)
        Mod(pi - log(exp(pi*1i)) / 1i) < .Machine$double.eps
        Mod(1+exp(pi*1i)) < .Machine$double.eps

