From 98d9552f0f94820d63abdc594120141ca136b0ad Mon Sep 17 00:00:00 2001
From: shippingwang <shipeng1108@163.com>
Date: Thu, 14 Mar 2019 07:56:31 +0000
Subject: [PATCH] update sqrt explaination, test=develop

---
 paddle/fluid/operators/activation_op.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/paddle/fluid/operators/activation_op.cc b/paddle/fluid/operators/activation_op.cc
index f79960317aa..c3479b47def 100644
--- a/paddle/fluid/operators/activation_op.cc
+++ b/paddle/fluid/operators/activation_op.cc
@@ -188,6 +188,9 @@ $$out = x - \\frac{e^{x} - e^{-x}}{e^{x} + e^{-x}}$$
 UNUSED constexpr char SqrtDoc[] = R"DOC(
 Sqrt Activation Operator.
 
+Please make sure legal input, when input a negative value closed to zero,
+you should add a small epsilon(1e-12) to avoid negative number caused by numerical errors.
+
 $out = \sqrt{x}$
 
 )DOC";
-- 
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