Add regression test for rotation

n3fit/src/n3fit/tests/test_rotations.py

@@ -0,0 +1,51 @@
+import numpy as np
+
+from n3fit.backends import operations as op
+from n3fit.layers import FkRotation, FlavourToEvolution
+
+
+def test_fk():
+    rotation = FkRotation()
+    gridpoints = 2
+    np.random.seed(0)
+    pdf = op.numpy_to_tensor(np.random.rand(1, gridpoints, 9))
+    pdf_rotated = rotation(pdf)
+    pdf_rotated_known = op.numpy_to_tensor(
+        [
+            [
+                [
+                    0.0,
+                    0.5488135,
+                    0.71518934,
+                    0.60276335,
+                    0.5448832,
+                    0.4236548,
+                    0.96366274,
+                    0.60276335,
+                    0.60276335,
+                    0.6458941,
+                    0.4375872,
+                    -3.0182784,
+                    0.5488135,
+                    0.5488135,
+                ],
+                [
+                    0.0,
+                    0.3834415,
+                    0.79172504,
+                    0.5288949,
+                    0.56804454,
+                    0.92559665,
+                    0.83261985,
+                    0.5288949,
+                    0.5288949,
+                    0.07103606,
+                    0.0871293,
+                    0.30256793,
+                    0.3834415,
+                    0.3834415,
+                ],
+            ]
+        ]
+    )
+    np.testing.assert_allclose(pdf_rotated.numpy(), pdf_rotated_known.numpy(), rtol=1e-5)