Added support for sigmoid function to the tensor module

Eigen/src/SVD/UpperBidiagonalization.h

@@ -380,6 +380,7 @@ UpperBidiagonalization<_MatrixType>& UpperBidiagonalization<_MatrixType>::comput
 {
   Index rows = matrix.rows();
   Index cols = matrix.cols();
+  EIGEN_ONLY_USED_FOR_DEBUG(rows);
   EIGEN_ONLY_USED_FOR_DEBUG(cols);
 
   eigen_assert(rows >= cols && "UpperBidiagonalization is only for Arices satisfying rows>=cols.");

unsupported/Eigen/CXX11/src/Tensor/TensorBase.h

@@ -116,6 +116,12 @@ class TensorBase<Derived, ReadOnlyAccessors>
       return unaryExpr(internal::scalar_tanh_op<Scalar>());
     }
 
+    EIGEN_DEVICE_FUNC
+    EIGEN_STRONG_INLINE const TensorCwiseUnaryOp<internal::scalar_sigmoid_op<Scalar>, const Derived>
+    sigmoid() const {
+      return unaryExpr(internal::scalar_sigmoid_op<Scalar>());
+    }
+
     EIGEN_DEVICE_FUNC
     EIGEN_STRONG_INLINE const TensorCwiseUnaryOp<internal::scalar_exp_op<Scalar>, const Derived>
     exp() const {

unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h

@@ -13,6 +13,36 @@
 namespace Eigen {
 namespace internal {
 
+
+/** \internal
+  * \brief Template functor to compute the sigmoid of a scalar
+  * \sa class CwiseUnaryOp, ArrayBase::sigmoid()
+  */
+template <typename T>
+struct scalar_sigmoid_op {
+  EIGEN_EMPTY_STRUCT_CTOR(scalar_sigmoid_op)
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE T operator()(const T& x) const {
+    const T one = T(1);
+    return one / (one + std::exp(-x));
+  }
+
+  template <typename Packet>
+  inline Packet packetOp(const Packet& x) const {
+    const Packet one = pset1<Packet>(1);
+    return pdiv(one, padd(one, pexp(pnegate(x))));
+  }
+};
+
+template <typename T>
+struct functor_traits<scalar_sigmoid_op<T> > {
+  enum {
+    Cost = NumTraits<T>::AddCost * 2 + NumTraits<T>::MulCost * 6,
+    PacketAccess = packet_traits<T>::HasAdd && packet_traits<T>::HasDiv &&
+                   packet_traits<T>::HasNegate && packet_traits<T>::HasExp
+  };
+};
+
+
 // Standard reduction functors
 template <typename T> struct SumReducer
 {

unsupported/test/CMakeLists.txt

@@ -109,6 +109,7 @@ if(EIGEN_TEST_CXX11)
   ei_add_test(cxx11_tensor_contraction "-std=c++0x")
   ei_add_test(cxx11_tensor_convolution "-std=c++0x")
   ei_add_test(cxx11_tensor_expr "-std=c++0x")
+  ei_add_test(cxx11_tensor_math "-std=c++0x")
   ei_add_test(cxx11_tensor_forced_eval "-std=c++0x")
   ei_add_test(cxx11_tensor_fixed_size "-std=c++0x")
   ei_add_test(cxx11_tensor_const "-std=c++0x")

unsupported/test/cxx11_tensor_math.cpp

@@ -0,0 +1,46 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2015 Benoit Steiner <benoit.steiner.goog@gmail.com>
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#include "main.h"
+
+#include <Eigen/CXX11/Tensor>
+
+using Eigen::Tensor;
+using Eigen::RowMajor;
+
+static void test_tanh()
+{
+  Tensor<float, 1> vec1({6});
+  vec1.setRandom();
+
+  Tensor<float, 1> vec2 = vec1.tanh();
+
+  for (int i = 0; i < 6; ++i) {
+    VERIFY_IS_APPROX(vec2(i), tanhf(vec1(i)));
+  }
+}
+
+static void test_sigmoid()
+{
+  Tensor<float, 1> vec1({6});
+  vec1.setRandom();
+
+  Tensor<float, 1> vec2 = vec1.sigmoid();
+
+  for (int i = 0; i < 6; ++i) {
+    VERIFY_IS_APPROX(vec2(i), 1.0f / (1.0f + std::exp(-vec1(i))));
+  }
+}
+
+
+void test_cxx11_tensor_math()
+{
+  CALL_SUBTEST(test_tanh());
+  CALL_SUBTEST(test_sigmoid());
+}