revise atan op (#6288)

* revise atan op

* use parametrized vistor API

* use new gtest macros

* Update docs/ops/arithmetic/Atan_1.md

Co-authored-by: Gabriele Galiero Casay <gabriele.galiero.casay@intel.com>

* Update docs/ops/arithmetic/Atan_1.md

Co-authored-by: Gabriele Galiero Casay <gabriele.galiero.casay@intel.com>

* Update ngraph/core/src/op/atan.cpp

Co-authored-by: Gabriele Galiero Casay <gabriele.galiero.casay@intel.com>

* update doc to follow the rules

* create type_prop for atan

* drop op_eval to be covered in backend

* add the missing type prop case

* add integer type ref impl

* fix clang issue

Co-authored-by: Gabriele Galiero Casay <gabriele.galiero.casay@intel.com>

docs/ops/arithmetic/Atan_1.md

@@ -6,31 +6,27 @@
 
 **Short description**: *Atan* performs element-wise inverse tangent (arctangent) operation with given tensor.
 
-**Attributes**:
+**Detailed description**:  Operation takes one input tensor and performs the element-wise inverse tangent function on a given input tensor, based on the following mathematical formula:
-
-    No attributes available.
-
-**Inputs**
-
-* **1**: An tensor of type *T*. **Required.**
-
-**Outputs**
-
-* **1**: The result of element-wise atan operation. A tensor of type *T*.
-
-**Types**
-
-* *T*: any numeric type.
-
-*atan* does the following with the input tensor *a*:
 
 \f[
 a_{i} = atan(a_{i})
 \f]
 
-**Examples**
+**Attributes**: *Atan* operation has no attributes.
 
-*Example 1*
+**Inputs**
+
+* **1**: A tensor of type *T* and arbitrary shape. **Required.**
+
+**Outputs**
+
+* **1**: The result of element-wise *Atan* applied to the input tensor. A tensor of type *T* and same shape as the input tensor.
+
+**Types**
+
+* *T*: any supported numeric type.
+
+**Examples**
 
 ```xml
 <layer ... type="Atan">

inference-engine/tests/functional/plugin/cpu/shared_tests_instances/single_layer_tests/activation.cpp

@@ -65,6 +65,7 @@ const std::map<ActivationTypes, std::vector<std::vector<float>>> activationTypes
 
 // List of operations that should be tested also with integer precision
 const std::map<ActivationTypes, std::vector<std::vector<float>>> intActivationTypes = {
+        {Atan,                  {}},
         {Negative,              {}},
         {Ceiling,               {}},
         {Cos,                   {}},

ngraph/core/include/ngraph/op/atan.hpp

@@ -19,8 +19,7 @@ namespace ngraph
             class NGRAPH_API Atan : public util::UnaryElementwiseArithmetic
             {
             public:
-                static constexpr NodeTypeInfo type_info{"Atan", 0};
+                NGRAPH_RTTI_DECLARATION;
-                const NodeTypeInfo& get_type_info() const override { return type_info; }
                 /// \brief Constructs an arctan operation.
                 Atan() = default;
 

ngraph/core/reference/include/ngraph/runtime/reference/atan.hpp

@@ -13,7 +13,8 @@ namespace ngraph
     {
         namespace reference
         {
-            template <typename T>
+            template <typename T,
+                      typename std::enable_if<!std::is_integral<T>::value, bool>::type = true>
             void atan(const T* arg, T* out, size_t count)
             {
                 for (size_t i = 0; i < count; i++)
@@ -21,6 +22,16 @@ namespace ngraph
                     out[i] = std::atan(arg[i]);
                 }
             }
+
+            template <typename T,
+                      typename std::enable_if<std::is_integral<T>::value, bool>::type = true>
+            void atan(const T* arg, T* out, size_t count)
+            {
+                for (size_t i = 0; i < count; i++)
+                {
+                    out[i] = std::roundl(std::atan(arg[i]));
+                }
+            }
         } // namespace reference
     }     // namespace runtime
 } // namespace ngraph

ngraph/core/src/op/atan.cpp

@@ -23,7 +23,7 @@
 using namespace std;
 using namespace ngraph;
 
-constexpr NodeTypeInfo op::Atan::type_info;
+NGRAPH_RTTI_DEFINITION(op::v0::Atan, "Atan", 0, util::UnaryElementwiseArithmetic);
 
 op::Atan::Atan(const Output<Node>& arg)
     : UnaryElementwiseArithmetic(arg)

ngraph/test/CMakeLists.txt

@@ -96,6 +96,7 @@ set(SRC
     type_prop/adaptive_max_pool.cpp
     type_prop/asin.cpp
     type_prop/assign.cpp
+    type_prop/atan.cpp
     type_prop/avg_pool.cpp
     type_prop/batch_norm.cpp
     type_prop/batch_to_space.cpp
@@ -228,6 +229,7 @@ set(SRC
     visitors/value_map.cpp
     visitors/op/adaptive_avg_pool.cpp
     visitors/op/adaptive_max_pool.cpp
+    visitors/op/atan.cpp
     visitors/op/batch_norm.cpp
     visitors/op/broadcast.cpp
     visitors/op/bucketize.cpp

ngraph/test/backend/atan.in.cpp

@@ -31,7 +31,7 @@ using namespace ngraph;
 static string s_manifest = "${MANIFEST}";
 using TestEngine = test::ENGINE_CLASS_NAME(${BACKEND_NAME});
 
-NGRAPH_TEST(${BACKEND_NAME}, atan)
+NGRAPH_TEST(${BACKEND_NAME}, atan_float)
 {
     Shape shape{11};
     auto A = make_shared<op::Parameter>(element::f32, shape);
@@ -53,3 +53,16 @@ NGRAPH_TEST(${BACKEND_NAME}, atan)
                                           1.32581766f});
     test_case.run();
 }
+
+NGRAPH_TEST(${BACKEND_NAME}, atan_int)
+{
+    Shape shape{5};
+    auto A = make_shared<op::Parameter>(element::i32, shape);
+    auto f = make_shared<Function>(make_shared<op::Atan>(A), ParameterVector{A});
+
+    auto test_case = test::TestCase<TestEngine>(f);
+    test_case.add_input<int32_t>({-2, -1, 0, 1, 2});
+    test_case.add_expected_output<int32_t>(shape,
+                                         {-1, -1, 0, 1, 1});
+    test_case.run();
+}

ngraph/test/type_prop/atan.cpp

@@ -0,0 +1,9 @@
+// Copyright (C) 2021 Intel Corporation
+// SPDX-License-Identifier: Apache-2.0
+//
+
+#include "unary_ops.hpp"
+
+using Type = ::testing::Types<ngraph::op::Atan>;
+
+INSTANTIATE_TYPED_TEST_SUITE_P(type_prop_atan, UnaryOperator, Type);

ngraph/test/visitors/op/atan.cpp

@@ -0,0 +1,12 @@
+// Copyright (C) 2021 Intel Corporation
+// SPDX-License-Identifier: Apache-2.0
+//
+
+#include "unary_ops.hpp"
+
+using Types = ::testing::Types<UnaryOperatorType<ngraph::op::v0::Atan, element::f32>>;
+
+INSTANTIATE_TYPED_TEST_SUITE_P(visitor_without_attribute,
+                              UnaryOperatorVisitor,
+                              Types,
+                              UnaryOperatorTypeName);