BUG: fix matmul with out=... array

matmul(x1, x2, out) does not broadcast x1, x2 against out, like
other ufuncs do.

Author: ev-br

torch_np/_binary_ufuncs.py

@@ -1,5 +1,7 @@
 from typing import Optional
 
+import torch
+
 from . import _helpers
 from ._detail import _binary_ufuncs
 from ._normalizations import (
@@ -12,7 +14,9 @@
 )
 
 __all__ = [
-    name for name in dir(_binary_ufuncs) if not name.startswith("_") and name != "torch"
+    name
+    for name in dir(_binary_ufuncs)
+    if not name.startswith("_") and name not in ["torch", "matmul"]
 ]
 
 
@@ -40,12 +44,49 @@ def wrapped(
         tensors = _helpers.ufunc_preprocess(
             (x1, x2), out, where, casting, order, dtype, subok, signature, extobj
         )
+        # now broadcast input tensors against the out=... array
+        if out is not None:
+            # XXX: need to filter out noop broadcasts if t.shape == out.shape?
+            shape = out.shape
+            tensors = tuple(torch.broadcast_to(t, shape) for t in tensors)
+
         result = torch_func(*tensors)
         return result, out
 
     return wrapped
 
 
+#
+# matmul is special in that its `out=...` array does not broadcast x1 and x2.
+# E.g. consider x1.shape = (5, 2) and x2.shape = (2, 3). Then `out.shape` is (5, 3).
+#
+@normalizer
+def matmul(
+    x1: ArrayLike,
+    x2: ArrayLike,
+    /,
+    out: Optional[NDArray] = None,
+    *,
+    casting="same_kind",
+    order="K",
+    dtype: DTypeLike = None,
+    subok: SubokLike = False,
+    signature=None,
+    extobj=None,
+    axes=None,
+    axis=None,
+) -> OutArray:
+    tensors = _helpers.ufunc_preprocess(
+        (x1, x2), out, True, casting, order, dtype, subok, signature, extobj
+    )
+    if axis is not None or axes is not None:
+        raise NotImplementedError
+
+    # NB: do not broadcast input tensors against the out=... array
+    result = _binary_ufuncs.matmul(*tensors)
+    return result, out
+
+
 #
 # For each torch ufunc implementation, decorate and attach the decorated name
 # to this module. Its contents is then exported to the public namespace in __init__.py
@@ -111,4 +152,4 @@ def modf(x, /, *args, **kwds):
     return rem, quot
 
 
-__all__ = __all__ + ["divmod", "modf"]
+__all__ = __all__ + ["divmod", "modf", "matmul"]

torch_np/_detail/_binary_ufuncs.py

@@ -45,9 +45,26 @@
 
 # work around torch limitations w.r.t. numpy
 def matmul(x, y):
-    # work around RuntimeError: expected scalar type Int but found Double
+    # work around:
+    #  - RuntimeError: expected scalar type Int but found Double
+    #  - RuntimeError: "addmm_impl_cpu_" not implemented for 'Bool'
+    #  - RuntimeError: "addmm_impl_cpu_" not implemented for 'Half'
     dtype = _dtypes_impl.result_type_impl((x.dtype, y.dtype))
-    x = _util.cast_if_needed(x, dtype)
-    y = _util.cast_if_needed(y, dtype)
+    is_bool = dtype == torch.bool
+    is_half = dtype == torch.float16
+
+    work_dtype = dtype
+    if is_bool:
+        work_dtype = torch.uint8
+    if is_half:
+        work_dtype = torch.float32
+
+    x = _util.cast_if_needed(x, work_dtype)
+    y = _util.cast_if_needed(y, work_dtype)
+
     result = torch.matmul(x, y)
+
+    if work_dtype != dtype:
+        result = result.to(dtype)
+
     return result

torch_np/_helpers.py

@@ -27,13 +27,6 @@ def ufunc_preprocess(
 
     if out_dtype:
         tensors = _util.typecast_tensors(tensors, out_dtype, casting)
-
-    # now broadcast input tensors against the out=... array
-    if out is not None:
-        # XXX: need to filter out noop broadcasts if t.shape == out.shape?
-        shape = out.shape
-        tensors = tuple(torch.broadcast_to(t, shape) for t in tensors)
-
     return tensors
 
 

torch_np/_unary_ufuncs.py

@@ -4,6 +4,8 @@
 
 from typing import Optional
 
+import torch
+
 from . import _helpers
 from ._detail import _unary_ufuncs
 from ._normalizations import (
@@ -43,6 +45,11 @@ def wrapped(
         tensors = _helpers.ufunc_preprocess(
             (x,), out, where, casting, order, dtype, subok, signature, extobj
         )
+        # now broadcast the input tensor against the out=... array
+        if out is not None:
+            # XXX: need to filter out noop broadcasts if t.shape == out.shape?
+            shape = out.shape
+            tensors = tuple(torch.broadcast_to(t, shape) for t in tensors)
         result = torch_func(*tensors)
         return result, out
 

torch_np/tests/numpy_tests/core/test_multiarray.py

@@ -5708,7 +5708,7 @@ class MatmulCommon:
     """
     # Should work with these types. Will want to add
     # "O" at some point
-    types = "?bhilqBefdFD"
+    types = "?bhilBefdFD"
 
     def test_exceptions(self):
         dims = [
@@ -5726,7 +5726,7 @@ def test_exceptions(self):
         for dt, (dm1, dm2) in itertools.product(self.types, dims):
             a = np.ones(dm1, dtype=dt)
             b = np.ones(dm2, dtype=dt)
-            assert_raises(ValueError, self.matmul, a, b)
+            assert_raises((RuntimeError, ValueError), self.matmul, a, b)
 
     def test_shapes(self):
         dims = [
@@ -5758,7 +5758,13 @@ def test_result_types(self):
                 res = self.matmul(*arg)
                 assert_(res.dtype == dt)
 
-            # vector vector returns scalars
+    @pytest.mark.xfail(reason='no scalars')
+    def test_result_types_2(self):
+        # in numpy, vector vector returns scalars
+        # we return a 0D array instead
+
+        for dt in self.types:
+            v = np.ones((1,)).astype(dt)
             if dt != "O":
                 res = self.matmul(v, v)
                 assert_(type(res) is np.dtype(dt).type)
@@ -5919,9 +5925,10 @@ def test_matrix_matrix_values(self):
         assert_equal(res, tgt12_21)
 
 
-@pytest.mark.xfail(reason='TODO: matmul (ufunc wrapping goes south?)')
 class TestMatmul(MatmulCommon):
-    matmul = np.matmul
+
+    def setup_method(self):
+        self.matmul = np.matmul
 
     def test_out_arg(self):
         a = np.ones((5, 2), dtype=float)
@@ -5941,17 +5948,17 @@ def test_out_arg(self):
         assert_array_equal(out, tgt, err_msg=msg)
 
         # test out with not allowed type cast (safe casting)
-        msg = "Cannot cast ufunc .* output"
+        msg = "Cannot cast"
         out = np.zeros((5, 2), dtype=np.int32)
         assert_raises_regex(TypeError, msg, self.matmul, a, b, out=out)
 
         # test out with type upcast to complex
         out = np.zeros((5, 2), dtype=np.complex128)
         c = self.matmul(a, b, out=out)
         assert_(c is out)
-        with suppress_warnings() as sup:
-            sup.filter(np.ComplexWarning, '')
-            c = c.astype(tgt.dtype)
+  #      with suppress_warnings() as sup:
+  #          sup.filter(np.ComplexWarning, '')
+        c = c.astype(tgt.dtype)
         assert_array_equal(c, tgt)
 
     def test_empty_out(self):
@@ -5961,7 +5968,7 @@ def test_empty_out(self):
         out = np.ones((1, 1, 1))
         assert self.matmul(arr, arr).shape == (0, 1, 1)
 
-        with pytest.raises(ValueError, match=r"non-broadcastable"):
+        with pytest.raises(ValueError, match="Bad size of the out array"):  # match=r"non-broadcastable"):
             self.matmul(arr, arr, out=out)
 
     def test_out_contiguous(self):
@@ -5974,7 +5981,7 @@ def test_out_contiguous(self):
         # test out non-contiguous
         out = np.ones((5, 2, 2), dtype=float)
         c = self.matmul(a, b, out=out[..., 0])
-        assert c.base is out
+        assert c._tensor._base is out._tensor     # FIXME: self.tensor (no underscore)
         assert_array_equal(c, tgt)
         c = self.matmul(a, v, out=out[:, 0, 0])
         assert_array_equal(c, tgt_mv)
@@ -6025,6 +6032,7 @@ def test_dot_equivalent(self, args):
         assert_equal(r1, r3)
 
 
+    @pytest.mark.skip(reason='object arrays')
     def test_matmul_exception_multiply(self):
         # test that matmul fails if `__mul__` is missing
         class add_not_multiply():
@@ -6034,6 +6042,7 @@ def __add__(self, other):
         with assert_raises(TypeError):
             b = np.matmul(a, a)
 
+    @pytest.mark.skip(reason='object arrays')
     def test_matmul_exception_add(self):
         # test that matmul fails if `__add__` is missing
         class multiply_not_add():
@@ -6043,6 +6052,7 @@ def __mul__(self, other):
         with assert_raises(TypeError):
             b = np.matmul(a, a)
 
+    @pytest.mark.xfail(reason="TODO: implement .view")
     def test_matmul_bool(self):
         # gh-14439
         a = np.array([[1, 0],[1, 1]], dtype=bool)