Conform Tensor to PointwiseMultiplicative. (#297)

Friend PR: swiftlang/swift#25772

Author: dan-zheng

Sources/TensorFlow/Core/Tensor.swift

@@ -500,11 +500,9 @@ extension Tensor: Codable where Scalar: Codable {
 //===------------------------------------------------------------------------------------------===//
 
 extension Tensor: AdditiveArithmetic where Scalar: Numeric {
-    /// A scalar zero tensor.
+    /// The scalar zero tensor.
     @inlinable
-    public static var zero: Tensor {
-        return Tensor(0)
-    }
+    public static var zero: Tensor { Tensor(0) }
 
     /// Adds two tensors and produces their sum.
     /// - Note: `+` supports broadcasting.
@@ -553,6 +551,26 @@ internal extension Tensor where Scalar: TensorFlowFloatingPoint {
     }
 }
 
+//===------------------------------------------------------------------------------------------===//
+// Multiplicative Group
+//===------------------------------------------------------------------------------------------===//
+
+extension Tensor: PointwiseMultiplicative where Scalar: Numeric {
+    /// The scalar one tensor.
+    @inlinable
+    public static var one: Tensor { Tensor(1) }
+
+    /// Returns the pointwise reciprocal of `self`.
+    @inlinable
+    public var reciprocal: Tensor { 1 / self }
+
+    /// Multiplies two tensors element-wise and produces their product.
+    /// - Note: `.*` supports broadcasting.
+    public static func .* (lhs: Tensor, rhs: Tensor) -> Tensor {
+        return lhs * rhs
+    }
+}
+
 //===------------------------------------------------------------------------------------------===//
 // Differentiable
 //===------------------------------------------------------------------------------------------===//