fix pinv (#2110)

python/src/array.cpp

@@ -197,6 +197,13 @@ void init_array(nb::module_& m) {
           "max",
           &mx::finfo::max,
           R"pbdoc(The largest representable number.)pbdoc")
+      .def_ro(
+          "eps",
+          &mx::finfo::eps,
+          R"pbdoc(
+            The difference between 1.0 and the next smallest
+            representable number larger than 1.0.
+          )pbdoc")
       .def_ro("dtype", &mx::finfo::dtype, R"pbdoc(The :obj:`Dtype`.)pbdoc")
       .def("__repr__", [](const mx::finfo& f) {
         std::ostringstream os;

python/tests/test_array.py

@@ -103,10 +103,12 @@ class TestDtypes(mlx_tests.MLXTestCase):
 
         self.assertEqual(mx.finfo(mx.float32).min, np.finfo(np.float32).min)
         self.assertEqual(mx.finfo(mx.float32).max, np.finfo(np.float32).max)
+        self.assertEqual(mx.finfo(mx.float32).eps, np.finfo(np.float32).eps)
         self.assertEqual(mx.finfo(mx.float32).dtype, mx.float32)
 
         self.assertEqual(mx.finfo(mx.float16).min, np.finfo(np.float16).min)
         self.assertEqual(mx.finfo(mx.float16).max, np.finfo(np.float16).max)
+        self.assertEqual(mx.finfo(mx.float16).eps, np.finfo(np.float16).eps)
         self.assertEqual(mx.finfo(mx.float16).dtype, mx.float16)
 
     def test_iinfo(self):

python/tests/test_linalg.py

@@ -232,6 +232,11 @@ class TestLinalg(mlx_tests.MLXTestCase):
         for M, M_plus in zip(AB, pinvs):
             self.assertTrue(mx.allclose(M @ M_plus @ M, M, rtol=0, atol=1e-3))
 
+        # Test singular matrix
+        A = mx.array([[4.0, 1.0], [4.0, 1.0]])
+        A_plus = mx.linalg.pinv(A, stream=mx.cpu)
+        self.assertTrue(mx.allclose(A @ A_plus @ A, A))
+
     def test_cholesky_inv(self):
         mx.random.seed(7)