Index: Objects/floatobject.c
===================================================================
--- Objects/floatobject.c	(revision 64402)
+++ Objects/floatobject.c	(working copy)
@@ -1204,8 +1204,45 @@
 ">>> (-.25).as_integer_ratio()\n"
 "(-1, 4)");
 
+static PyObject *
+_float_to_base(PyFloatObject *v, unaryfunc int_to_base)
+{
+	PyObject *mant, *converted, *result;
+	double x, fr;
+	int i, exponent;
 
+	CONVERT_TO_DOUBLE(((PyObject *)v), x);
+	if (!Py_IS_FINITE(x))
+		return PyObject_Repr((PyObject *)v);
+	fr = frexp(x, &exponent);
+	for (i=0; i<300 && fr != floor(fr) ; i++) {
+		fr *= 2.0;
+		exponent--;
+	}
+	mant = PyLong_FromDouble(floor(fr));
+	if (mant == NULL)
+		return NULL;
+	converted = int_to_base(mant);
+	Py_DECREF(mant);
+	result = PyString_FromFormat("%s * 2.0 ** %d",
+						PyString_AS_STRING(converted), exponent);
+	Py_DECREF(converted);
+	return result;
+}
+
 static PyObject *
+float_hex(PyFloatObject *v)
+{
+	return _float_to_base(v, PyLong_Type.tp_as_number->nb_hex);
+}
+
+static PyObject *
+float_oct(PyFloatObject *v)
+{
+	return _float_to_base(v, PyLong_Type.tp_as_number->nb_oct);
+}
+
+static PyObject *
 float_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds);
 
 static PyObject *
@@ -1490,8 +1527,8 @@
 	float_trunc, 	/*nb_int*/
 	float_trunc, 	/*nb_long*/
 	float_float,	/*nb_float*/
-	0,		/* nb_oct */
-	0,		/* nb_hex */
+	(unaryfunc)float_oct,		/* nb_oct */
+	(unaryfunc)float_hex,		/* nb_hex */
 	0,		/* nb_inplace_add */
 	0,		/* nb_inplace_subtract */
 	0,		/* nb_inplace_multiply */
Index: Lib/test/test_builtin.py
===================================================================
--- Lib/test/test_builtin.py	(revision 64402)
+++ Lib/test/test_builtin.py	(working copy)
@@ -631,6 +631,10 @@
         self.assertEqual(hex(-16), '-0x10')
         self.assertEqual(hex(-16L), '-0x10L')
         self.assertRaises(TypeError, hex, {})
+        self.assertEqual(hex(3.125), '0x19L * 2.0 ** -3')
+        for i in range(100):
+            x = random.expovariate(.05)
+            self.assertEqual(eval(hex(x)), x, (x, hex(x), eval(hex(x))))
 
     def test_id(self):
         id(None)
@@ -914,6 +918,10 @@
         self.assertEqual(oct(-100), '-0144')
         self.assertEqual(oct(-100L), '-0144L')
         self.assertRaises(TypeError, oct, ())
+        self.assertEqual(oct(3.125), '031L * 2.0 ** -3')
+        for i in range(100):
+            x = random.expovariate(.05)
+            self.assertEqual(eval(oct(x)), x)
 
     def write_testfile(self):
         # NB the first 4 lines are also used to test input and raw_input, below