chore: import upstream snapshot with attribution

2026-07-13 13:30:25 +08:00
commit f19b2512d7
562 changed files with 38082 additions and 0 deletions
@@ -0,0 +1,36 @@
+import numpy as np
+from prml.nn.tensor.constant import Constant
+from prml.nn.tensor.tensor import Tensor
+from prml.nn.function import Function
+
+
+class BroadcastTo(Function):
+    """
+    Broadcast a tensor to an new shape
+    """
+
+    def forward(self, x, shape):
+        x = self._convert2tensor(x)
+        self.x = x
+        output = np.broadcast_to(x.value, shape)
+        if isinstance(self.x, Constant):
+            return Constant(output)
+        return Tensor(output, function=self)
+
+    def backward(self, delta):
+        dx = delta
+        if delta.ndim != self.x.ndim:
+            dx = dx.sum(axis=tuple(range(dx.ndim - self.x.ndim)))
+            if isinstance(dx, np.number):
+                dx = np.array(dx)
+        axis = tuple(i for i, len_ in enumerate(self.x.shape) if len_ == 1)
+        if axis:
+            dx = dx.sum(axis=axis, keepdims=True)
+        self.x.backward(dx)
+
+
+def broadcast_to(x, shape):
+    """
+    Broadcast a tensor to an new shape
+    """
+    return BroadcastTo().forward(x, shape)