

   HHiigghhllyy CCoommppoossiittee NNuummbbeerrss

        nextn(n, factors=c(2,3,5))

   AArrgguummeennttss::

          n: an integer.

    factors: a vector of positive integer factors.

   DDeessccrriippttiioonn::

        `nextn' returns the smallest integer, greater than or
        equal to `n', which can be obtained as a product of
        powers of the values contained in `factors'.  `nextn'
        is intended to be used to find a suitable length to
        zero-pad the argument of `fft' to so that the transform
        is computed quickly.  The default value for `factors'
        ensures this.

   SSeeee AAllssoo::

        `convolve', `fft'.

   EExxaammpplleess::

        nextn(1001) # 1024
        table(sapply(599:630, nextn))

