divmod

/*
 *  call-seq:
 *     num.divmod( aNumeric ) -> anArray
 *
 *  Returns an array containing the quotient and modulus obtained by
 *  dividing <i>num</i> by <i>aNumeric</i>. If <code>q, r =
 *  x.divmod(y)</code>, then
 *
 *      q = floor(float(x)/float(y))
 *      x = q*y + r
 *
 *  The quotient is rounded toward -infinity, as shown in the following table:
 *
 *     a    |  b  |  a.divmod(b)  |   a/b   | a.modulo(b) | a.remainder(b)
 *    ------+-----+---------------+---------+-------------+---------------
 *     13   |  4  |   3,    1     |   3     |    1        |     1
 *    ------+-----+---------------+---------+-------------+---------------
 *     13   | -4  |  -4,   -3     |  -3     |   -3        |     1
 *    ------+-----+---------------+---------+-------------+---------------
 *    -13   |  4  |  -4,    3     |  -4     |    3        |    -1
 *    ------+-----+---------------+---------+-------------+---------------
 *    -13   | -4  |   3,   -1     |   3     |   -1        |    -1
 *    ------+-----+---------------+---------+-------------+---------------
 *     11.5 |  4  |   2,    3.5   |   2.875 |    3.5      |     3.5
 *    ------+-----+---------------+---------+-------------+---------------
 *     11.5 | -4  |  -3,   -0.5   |  -2.875 |   -0.5      |     3.5
 *    ------+-----+---------------+---------+-------------+---------------
 *    -11.5 |  4  |  -3,    0.5   |  -2.875 |    0.5      |    -3.5
 *    ------+-----+---------------+---------+-------------+---------------
 *    -11.5 | -4  |   2    -3.5   |   2.875 |   -3.5      |    -3.5
 *
 *
 *  Examples
 *     11.divmod(3)         #=> [3, 2]
 *     11.divmod(-3)        #=> [-4, -1]
 *     11.divmod(3.5)       #=> [3, 0.5]
 *     (-11).divmod(3.5)    #=> [-4, 3.0]
 *     (11.5).divmod(3.5)   #=> [3, 1.0]
 */

static VALUE
num_divmod(x, y)
    VALUE x, y;
{
    return rb_assoc_new(num_div(x, y), rb_funcall(x, '%', 1, y));
}