48   t.dbl = 0.0;  in cbrt()
49   temp.dbl = x;  in cbrt()
68     t.dbl *= temp.dbl;  in cbrt()
77   r = t.dbl * t.dbl / temp.dbl;  in cbrt()
78   s = C + r * t.dbl;  in cbrt()
79   t.dbl *= G + F / (s + E + D / s);  in cbrt()
86   s = t.dbl * t.dbl; /* t*t is exact */  in cbrt()
87   r = temp.dbl / s;  in cbrt()
88   w = t.dbl + t.dbl;  in cbrt()
89   r = (r - t.dbl) / (w + r); /* r-s is exact */  in cbrt()
90   t.dbl = t.dbl + (t.dbl * r);  in cbrt()
94   return (t.dbl);  in cbrt()