From e515f18dd857d2f9f986955cd76208a965eb5c5c Mon Sep 17 00:00:00 2001
From: qijun <qijun1994@hotmail.com>
Date: Thu, 14 Sep 2017 10:26:41 +0800
Subject: [PATCH] add tanh and sqrt activation operators

---
 paddle/operators/activation_op.h | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/paddle/operators/activation_op.h b/paddle/operators/activation_op.h
index 0b7e171e7..4421c1095 100644
--- a/paddle/operators/activation_op.h
+++ b/paddle/operators/activation_op.h
@@ -99,5 +99,36 @@ struct ReluGradFunctor {
   }
 };
 
+struct TanhFunctor {
+  template <typename Device, typename X, typename Y>
+  void operator()(Device d, X x, Y y) {
+    y.device(d) = x.tanh();
+  }
+};
+
+template <typename T>
+struct TanhGradFunctor {
+  template <typename Device, typename X, typename Y, typename dY, typename dX>
+  void operator()(Device d, X x, Y y, dY dy, dX dx) {
+    dx.device(d) = dy * (T(1) - y * y);
+  }
+};
+
+struct SqrtFunctor {
+  template <typename Device, typename X, typename Y>
+  void operator()(Device d, X x, Y y) {
+    y.device(d) = x.sqrt();
+  }
+};
+
+template <typename T>
+struct SqrtGradFunctor {
+  template <typename Device, typename X, typename Y, typename dY, typename dX>
+  void operator()(Device d, X x, Y y, dY dy, dX dx) {
+    const T y_conj = Eigen::numext::conj(y);
+    dx.device(d) = static_cast<T>(0.5) * dy / y_conj;
+  }
+};
+
 }  // namespace operators
 }  // namespace paddle
-- 
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