Added atan operator

ops/opset13/atan.go

@@ -0,0 +1,75 @@
+package opset13
+
+import (
+	"math"
+
+	"github.com/advancedclimatesystems/gonnx/onnx"
+	"github.com/advancedclimatesystems/gonnx/ops"
+	"gorgonia.org/tensor"
+)
+
+// Atan represents the ONNX atan operator.
+type Atan struct{}
+
+// newAtan creates a new atan operator.
+func newAtan() ops.Operator {
+	return &Atan{}
+}
+
+// Init initializes the atan operator.
+func (a *Atan) Init(_ []*onnx.AttributeProto) error {
+	return nil
+}
+
+// Apply applies the atan operator.
+func (a *Atan) Apply(inputs []tensor.Tensor) ([]tensor.Tensor, error) {
+	var (
+		out tensor.Tensor
+		err error
+	)
+
+	switch inputs[0].Dtype() {
+	case tensor.Float32:
+		out, err = inputs[0].Apply(atan[float32])
+	case tensor.Float64:
+		out, err = inputs[0].Apply(atan[float64])
+	default:
+		return nil, ops.ErrInvalidInputType(0, inputs[0].Dtype().String(), a)
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	return []tensor.Tensor{out}, nil
+}
+
+// ValidateInputs validates the inputs that will be given to Apply for this operator.
+func (a *Atan) ValidateInputs(inputs []tensor.Tensor) ([]tensor.Tensor, error) {
+	return ops.ValidateInputs(a, inputs)
+}
+
+// GetMinInputs returns the minimum number of input tensors this operator expects.
+func (a *Atan) GetMinInputs() int {
+	return 1
+}
+
+// GetMaxInputs returns the maximum number of input tensors this operator expects.
+func (a *Atan) GetMaxInputs() int {
+	return 1
+}
+
+// GetInputTypeConstraints returns a list. Every element represents a set of allowed tensor dtypes
+// for the corresponding input tensor.
+func (a *Atan) GetInputTypeConstraints() [][]tensor.Dtype {
+	return [][]tensor.Dtype{{tensor.Float32, tensor.Float64}}
+}
+
+// String implements the stringer interface, and can be used to format errors or messages.
+func (a *Atan) String() string {
+	return "atan operator"
+}
+
+func atan[T ops.FloatType](x T) T {
+	return T(math.Atan(float64(x)))
+}

ops/opset13/atan_test.go

@@ -0,0 +1,99 @@
+package opset13
+
+import (
+	"testing"
+
+	"github.com/advancedclimatesystems/gonnx/ops"
+	"github.com/stretchr/testify/assert"
+	"gorgonia.org/tensor"
+)
+
+func TestAtanInit(t *testing.T) {
+	a := &Atan{}
+
+	// since 'atan' does not have any attributes we pass in nil. This should not
+	// fail initializing the atan.
+	err := a.Init(nil)
+	assert.Nil(t, err)
+}
+
+func TestAtan(t *testing.T) {
+	tests := []struct {
+		atan     *Atan
+		backing  []float32
+		shape    []int
+		expected []float32
+	}{
+		{
+			&Atan{},
+			[]float32{1, 2, 3, 4},
+			[]int{2, 2},
+			[]float32{0.7853982, 1.1071488, 1.2490457, 1.3258177},
+		},
+		{
+			&Atan{},
+			[]float32{1, 2, 3, 4},
+			[]int{1, 4},
+			[]float32{0.7853982, 1.1071488, 1.2490457, 1.3258177},
+		},
+		{
+			&Atan{},
+			[]float32{2, 2, 2, 2},
+			[]int{1, 4},
+			[]float32{1.1071488, 1.1071488, 1.1071488, 1.1071488},
+		},
+	}
+
+	for _, test := range tests {
+		inputs := []tensor.Tensor{
+			ops.TensorWithBackingFixture(test.backing, test.shape...),
+		}
+
+		res, err := test.atan.Apply(inputs)
+		assert.Nil(t, err)
+
+		assert.Nil(t, err)
+		assert.Equal(t, test.expected, res[0].Data())
+	}
+}
+
+func TestInputValidationAtan(t *testing.T) {
+	tests := []struct {
+		inputs []tensor.Tensor
+		err    error
+	}{
+		{
+			[]tensor.Tensor{
+				ops.TensorWithBackingFixture([]float32{1, 2}, 2),
+			},
+			nil,
+		},
+		{
+			[]tensor.Tensor{
+				ops.TensorWithBackingFixture([]float64{1, 2}, 2),
+			},
+			nil,
+		},
+		{
+			[]tensor.Tensor{},
+			ops.ErrInvalidInputCount(0, &Atan{}),
+		},
+		{
+			[]tensor.Tensor{
+				ops.TensorWithBackingFixture([]int{1, 2}, 2),
+			},
+			ops.ErrInvalidInputType(0, "int", &Atan{}),
+		},
+	}
+
+	for _, test := range tests {
+		atan := &Atan{}
+		validated, err := atan.ValidateInputs(test.inputs)
+
+		assert.Equal(t, test.err, err)
+
+		if test.err == nil {
+			assert.Equal(t, test.inputs, validated)
+		}
+	}
+}

ops/opset13/opset13.go

@@ -9,6 +9,7 @@ var operators13 = map[string]func() ops.Operator{
 	"Acos":            newAcos,
 	"Acosh":           newAcosh,
 	"Add":             newAdd,
+        "Atan": newAtan,
 	"Cast":            newCast,
 	"Concat":          newConcat,
 	"Constant":        newConstant,

ops/opset13/opset13_test.go

@@ -33,6 +33,11 @@ func TestGetOperator(t *testing.T) {
 			newAdd(),
 			nil,
 		},
+                {
+                    "Atan",
+                    newAtan(),
+                    nil,
+                },
 		{
 			"Cast",
 			newCast(),

ops_test.go

@@ -278,6 +278,8 @@ var expectedTests = []string{
 	"test_acosh_example",
 	"test_add",
 	"test_add_bcast",
+        "test_atan",
+        "test_atan_example",
 	"test_cast_DOUBLE_to_FLOAT",
 	"test_cast_FLOAT_to_DOUBLE",
 	"test_concat_1d_axis_0",