Added Softmax to Maths folder (#516)

Maths/test/Softmax.test.js

@@ -0,0 +1,12 @@
+import { Softmax } from '../Softmax'
+
+describe('Softmax', () => {
+  it('should return equal distribution of 1 for equal input values', () => {
+    expect(Softmax([1, 1])).toEqual([0.5, 0.5])
+    expect(Softmax([1, 1, 1, 1])).toEqual([0.25, 0.25, 0.25, 0.25])
+  })
+
+  it('should return values which sum to the value of 1', () => {
+    expect(Softmax([1, 2, 3, 4]).reduce((a, b) => a + b, 0)).toEqual(1)
+  })
+})