added basis tests

test/basis.json

 [
   {
+    "name": "Linear and open B-splines",
     "degree": 1,
-    "pseudo": [0, 0.125, 0.25, 0.5, 0.75, 0.875, 1],
+    "pseudo": [0, 0.05, 0.25, 0.5, 0.75, 0.95, 1],
     "kernel_size": [5],
     "is_open_spline": [1],
-    "expected_basis": [[1, 0], [0.5, 0.5], [1, 0], [1, 0], [1, 0], [0.5, 0.5], [1, 0]],
+    "expected_basis": [[1, 0], [0.8, 0.2], [1, 0], [1, 0], [1, 0], [0.2, 0.8], [1, 0]],
     "expected_index": [[0, 1], [0, 1], [1, 2], [2, 3], [3, 4], [3, 4], [4, 0]]
   },
   {
+    "name": "Linear and closed B-splines",
     "degree": 1,
-    "pseudo": [0, 0.125, 0.25, 0.5, 0.75, 0.875, 1],
+    "pseudo": [0, 0.05, 0.25, 0.5, 0.75, 0.95, 1],
     "kernel_size": [4],
     "is_open_spline": [0],
-    "expected_basis": [[1, 0], [0.5, 0.5], [1, 0], [1, 0], [1, 0], [0.5, 0.5], [1, 0]],
+    "expected_basis": [[1, 0], [0.8, 0.2], [1, 0], [1, 0], [1, 0], [0.2, 0.8], [1, 0]],
     "expected_index": [[0, 1], [0, 1], [1, 2], [2, 3], [3, 0], [3, 0], [0, 1]]
   },
   {
+    "name": "Quadratic and open B-splines",
+    "degree": 2,
+    "pseudo": [0, 0.05, 0.25, 0.5, 0.75, 0.95, 1],
+    "kernel_size": [6],
+    "is_open_spline": [1],
+    "expected_basis": [[0.5, 0.5, 0], [0.32, 0.66, 0.02], [0.5, 0.5, 0], [0.5, 0.5, 0], [0.5, 0.5, 0], [0.02, 0.66, 0.32], [0.5, 0.5, 0]],
+    "expected_index": [[0, 1, 2], [0, 1, 2], [1, 2, 3], [2, 3, 4], [3, 4, 5], [3, 4, 5], [4, 5, 0]]
+  },
+  {
+    "name": "Quadratic and closed B-splines",
+    "degree": 2,
+    "pseudo": [0, 0.05, 0.25, 0.5, 0.75, 0.95, 1],
+    "kernel_size": [4],
+    "is_open_spline": [0],
+    "expected_basis": [[0.5, 0.5, 0], [0.32, 0.66, 0.02], [0.5, 0.5, 0], [0.5, 0.5, 0], [0.5, 0.5, 0], [0.02, 0.66, 0.32], [0.5, 0.5, 0]],
+    "expected_index": [[0, 1, 2], [0, 1, 2], [1, 2, 3], [2, 3, 0], [3, 0, 1], [3, 0, 1], [0, 1, 2]]
+  },
+  {
+    "name": "Cubic and open B-splines",
+    "degree": 3,
+    "pseudo": [0, 0.05, 0.25, 0.5, 0.75, 0.95, 1],
+    "kernel_size": [7],
+    "is_open_spline": [1],
+    "expected_basis": [[0.16667, 0.6667, 0.1667, 0], [0.0853, 0.6307, 0.2827, 0.00133], [0.1667, 0.6667, 0.1667, 0], [0.1667, 0.6667, 0.1667, 0], [0.1667, 0.6667, 0.1667, 0], [0.00133, 0.2827, 0.6307, 0.0853], [0.1667, 0.6667, 0.1667, 0]],
+    "expected_index": [[0, 1, 2, 3], [0, 1, 2, 3], [1, 2, 3, 4], [2, 3, 4, 5], [3, 4, 5, 6], [3, 4, 5, 6], [4, 5, 6, 0]]
+  },
+  {
+    "name": "Cubic and closed B-splines",
+    "degree": 3,
+    "pseudo": [0, 0.05, 0.25, 0.5, 0.75, 0.95, 1],
+    "kernel_size": [4],
+    "is_open_spline": [0],
+    "expected_basis": [[0.16667, 0.6667, 0.1667, 0], [0.0853, 0.6307, 0.2827, 0.00133], [0.1667, 0.6667, 0.1667, 0], [0.1667, 0.6667, 0.1667, 0], [0.1667, 0.6667, 0.1667, 0], [0.00133, 0.2827, 0.6307, 0.0853], [0.1667, 0.6667, 0.1667, 0]],
+    "expected_index": [[0, 1, 2, 3], [0, 1, 2, 3], [1, 2, 3, 0], [2, 3, 0, 1], [3, 0, 1, 2], [3, 0, 1, 2], [0, 1, 2, 3]]
+  },
+  {
+    "name": "Two-dimensional pseudo-coordinates",
     "degree": 1,
     "pseudo": [[0.125, 0.5], [0.5, 0.5], [0.75, 0.125]],
     "kernel_size": [5, 5],

test/test_basis.py

@@ -24,5 +24,7 @@ def test_spline_basis_cpu(tensor, i):
     expected_index = torch.ByteTensor(data[i]['expected_index'])
 
     basis, index = spline_basis(degree, pseudo, kernel_size, is_open_spline, K)
-    assert basis.tolist() == expected_basis.tolist()
+    basis = [pytest.approx(x, 0.01) for x in basis.view(-1).tolist()]
+
+    assert basis == expected_basis.view(-1).tolist()
     assert index.tolist() == expected_index.tolist()

torch_spline_conv/src/generic/cpu.c

@@ -15,9 +15,9 @@
       for (d = 0; d < D; d++) { \
         offset /= kernel_size_data[d]; \
         k_mod = k % (M + 1); \
-        k /= (M + 1); \
+        k /= M + 1; \
         value = *(pseudo_data + d * pseudo_stride) * (kernel_size_data[d] - M * is_open_spline_data[d]); \
-        i += ((((int64_t) value) + k_mod) % kernel_size_data[d]) * offset; \
+        i += (((int64_t) value + k_mod) % kernel_size_data[d]) * offset; \
         value -= floor(value); \
         CODE \
         b *= value; \