diff --git a/src/ansys/dpf/core/field_base.py b/src/ansys/dpf/core/field_base.py
index 05d9612314..f9303ad60a 100644
--- a/src/ansys/dpf/core/field_base.py
+++ b/src/ansys/dpf/core/field_base.py
@@ -2,6 +2,8 @@
 import warnings
 
 from abc import abstractmethod
+from typing import Union, List
+
 from ansys.dpf.gate.generated import field_abstract_api
 
 from ansys.dpf.core import scoping
@@ -358,15 +360,19 @@ def get_entity_data_by_id(self, id):
         pass
 
     @abstractmethod
-    def append(self, data, scopingid):
-        """Add an entity data to the existing data.
+    def append(
+        self,
+        data: Union[List[int], List[float], List[List[float]], List, np.ndarray],
+        scopingid: Union[int, List[int]]
+    ):
+        """Add data to the field for an entity or a list of entities.
 
         Parameters
         ----------
-        data : list of int, double, or array
-          Data in the entity.
-        scopingid : int
-            ID of the scoping.
+        data:
+          Data for the entity or list of entities.
+        scopingid:
+          ID or list of IDs of the entities to add data for.
 
         Examples
         --------
diff --git a/tests/test_math.py b/tests/test_math.py
new file mode 100644
index 0000000000..a0ba89d662
--- /dev/null
+++ b/tests/test_math.py
@@ -0,0 +1,89 @@
+import numpy as np
+
+import ansys.dpf.core as dpf
+
+
+def test_math_matrix_inverse_3d():
+    dim = 3
+    real_field = dpf.fields_factory.create_matrix_field(
+        num_entities=1,
+        num_lines=dim,
+        num_col=dim,
+    )
+    real_field.unit = "m"
+    values = [1.0, 1.0, 1.0,
+              4.0, 0.0, 0.0,
+              1.0, 1.0, 1.0]
+    real_field.append(values, 1)
+
+    img_field = dpf.fields_factory.create_matrix_field(
+        num_entities=1,
+        num_lines=dim,
+        num_col=dim,
+    )
+    img_field.unit = "m"
+    values = [0.3, 0.0, 0.0,
+              1.0, 1.0, 2.0,
+              0.0, 0.0, 0.1]
+    img_field.append(values, 1)
+
+    fc_in = dpf.fields_container_factory.over_time_freq_complex_fields_container(
+        real_fields={1.0: real_field}, imaginary_fields={1.0: img_field}, time_freq_unit="s"
+    )
+
+    fc_out = dpf.operators.math.matrix_inverse(fields_container=fc_in).eval()
+
+    print(fc_out)
+    print(fc_out[0])
+    assert fc_out[0].unit == "m^-1"
+    real_inverse_values = [1.4551, 0.1564, -1.5642,
+                           -5.1946, -0.6584, 6.5842,
+                           4.3652, 0.4693, -4.6926]
+    assert np.allclose(fc_out[0].data, real_inverse_values, atol=0.0001)
+
+    print(fc_out[1])
+    assert fc_out[1].unit == "m^-1"
+    img_inverse_values = [-1.2477, -0.1091, 1.0913,
+                          -5.4456, 0.3896, 6.1040,
+                          6.2568, -0.3274, -6.7261]
+    assert np.allclose(fc_out[1].data, img_inverse_values, atol=0.0001)
+
+
+def test_math_matrix_inverse_2d():
+    dim = 2
+    real_field = dpf.fields_factory.create_matrix_field(
+        num_entities=1,
+        num_lines=dim,
+        num_col=dim,
+    )
+    real_field.unit = "m"
+    values = [0.0, 1.0,
+              2.0, 3.0]
+    real_field.append(values, 1)
+
+    img_field = dpf.fields_factory.create_matrix_field(
+        num_entities=1,
+        num_lines=dim,
+        num_col=dim,
+    )
+    img_field.unit = "m"
+    values = [1.0, 1.0,
+              1.0, 1.0]
+    img_field.append(values, 1)
+
+    fc_in = dpf.fields_container_factory.over_time_freq_complex_fields_container(
+        real_fields={1.0: real_field}, imaginary_fields={1.0: img_field}, time_freq_unit="s"
+    )
+
+    fc_out = dpf.operators.math.matrix_inverse(fields_container=fc_in).eval()
+
+    print(fc_out)
+    print(fc_out[0])
+    assert fc_out[0].unit == "m^-1"
+    real_inverse_values = [-1.5, 0.5, 1.0, 0.0]
+    assert np.allclose(fc_out[0].data, real_inverse_values, atol=0.0001)
+
+    print(fc_out[1])
+    assert fc_out[1].unit == "m^-1"
+    img_inverse_values = [-0.5, 0.5,  0.5, -0.5]
+    assert np.allclose(fc_out[1].data, img_inverse_values, atol=0.0001)