void
_num(class,x)
  SV*	x
  INIT:
    AV*	a;
    NV	fac;
    SV*	temp;
    NV	num;
    I32	elems;
    I32	index;
    NV	BASE;

  CODE:
    a = (AV*)SvRV(x);			/* ref to aray, don't check ref */
    elems = av_len(a);			/* number of elems in array */

    if (elems == 0)			/* only one element? */
      {
      ST(0) = *av_fetch(a, 0, 0);	/* fetch first (only) element */
      XSRETURN(1);			/* return it */
      }
    fac = 1.0;				/* factor */
    index = 0;
    num = 0.0;
    BASE = XS_BASE;
    while (index <= elems)
      {
      temp = *av_fetch(a, index, 0);	/* fetch current element */
      num += fac * SvNV(temp);
      fac *= BASE;
      index++;
      }
    ST(0) = newSVnv(num);