Minor updates to address a few issues (#537)

* docs on arg indices return type

* arange with nan

* undo isort

Author: awni

mlx/ops.cpp

@@ -79,7 +79,14 @@ array arange(
     msg << bool_ << " not supported for arange.";
     throw std::invalid_argument(msg.str());
   }
-  int size = std::max(static_cast<int>(std::ceil((stop - start) / step)), 0);
+  if (std::isnan(start) || std::isnan(step) || std::isnan(stop)) {
+    throw std::invalid_argument("[arange] Cannot compute length.");
+  }
+  double real_size = std::ceil((stop - start) / step);
+  if (std::isnan(real_size)) {
+    throw std::invalid_argument("[arange] Cannot compute length.");
+  }
+  int size = std::max(static_cast<int>(real_size), 0);
   return array(
       {size},
       dtype,

python/src/ops.cpp

@@ -2254,7 +2254,7 @@ void init_ops(py::module_& m) {
               singleton dimensions, defaults to `False`.
 
         Returns:
-            array: The output array with the indices of the minimum values.
+            array: The ``uint32`` array with the indices of the minimum values.
       )pbdoc");
   m.def(
       "argmax",
@@ -2287,7 +2287,7 @@ void init_ops(py::module_& m) {
               singleton dimensions, defaults to `False`.
 
         Returns:
-            array: The output array with the indices of the maximum values.
+            array: The ``uint32`` array with the indices of the maximum values.
       )pbdoc");
   m.def(
       "sort",
@@ -2343,7 +2343,7 @@ void init_ops(py::module_& m) {
               If unspecified, it defaults to -1 (sorting over the last axis).
 
         Returns:
-            array: The indices that sort the input array.
+            array: The ``uint32`` array containing indices that sort the input.
       )pbdoc");
   m.def(
       "partition",
@@ -2416,7 +2416,7 @@ void init_ops(py::module_& m) {
               If unspecified, it defaults to ``-1``.
 
         Returns:
-            array: The indices that partition the input array.
+            array: The `uint32`` array containing indices that partition the input.
       )pbdoc");
   m.def(
       "topk",

python/tests/test_ops.py

@@ -980,6 +980,17 @@ def test_split(self):
         self.assertEqual(z.tolist(), [5, 6, 7])
 
     def test_arange_overload_dispatch(self):
+        with self.assertRaises(ValueError):
+            a = mx.arange(float("nan"), 1, 5)
+        with self.assertRaises(ValueError):
+            a = mx.arange(0, float("nan"), 5)
+        with self.assertRaises(ValueError):
+            a = mx.arange(0, 2, float("nan"))
+        with self.assertRaises(ValueError):
+            a = mx.arange(0, float("inf"), float("inf"))
+        with self.assertRaises(ValueError):
+            a = mx.arange(float("inf"), 1, float("inf"))
+
         a = mx.arange(5)
         expected = [0, 1, 2, 3, 4]
         self.assertListEqual(a.tolist(), expected)