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 +1,27 @@
+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 Softplus(Function):
+
+    def forward(self, x):
+        x = self._convert2tensor(x)
+        self.x = x
+        output = np.maximum(x.value, 0) + np.log1p(np.exp(-np.abs(x.value)))
+        if isinstance(x, Constant):
+            return Constant(output)
+        return Tensor(output, function=self)
+
+    def backward(self, delta):
+        dx = (np.tanh(0.5 * self.x.value) * 0.5 + 0.5) * delta
+        self.x.backward(dx)
+
+
+def softplus(x):
+    """
+    smoothed rectified linear unit
+    log(1 + exp(x))
+    """
+    return Softplus().forward(x)