added softmax

README.md

@@ -32,6 +32,7 @@ The following functions are supported:
 - [round](#round)
 - [root](#root)
 - [sign](#sign)
+- [softmax](#softmax)
 - [sort](#sort)
 - [square_root](#square_root)
 - [subtract](#subtract)
@@ -300,6 +301,16 @@ sort(["1", "2", "3"], { direction: "descending" })
 ["3", "2", "1"]
 ```
 
+### softmax
+Calculate the [softmax function](https://en.wikipedia.org/wiki/Softmax_function)
+```js
+import softmax from "preciso/softmax.js";
+
+// example data from https://en.wikipedia.org/wiki/Softmax_function
+softmax(["1", "2", "3", "4", "1", "2", "3"], { max_decimal_digits: 8 });
+["0.02364054", "0.06426166", "0.1746813", "0.474833", "0.02364054", "0.06426166", "0.1746813"]
+```
+
 ### square root
 ```js
 import square_root from "preciso/square_root.js";

build_e.js

@@ -0,0 +1,11 @@
+const start = performance.now();
+console.log("[preciso] building Euler's Number");
+
+const fs = require("node:fs");
+const e = require("./eulers_number.js");
+
+const str = e({ steps: 1000, max_decimal_digits: 1000 });
+
+fs.writeFileSync("./constants/e.js", `module.exports = { E: "${str}" };\n`);
+
+console.log("[preciso] building Euler's Number took " + Math.round((performance.now() - start) / 1000) + " seconds");

exp.js

@@ -5,8 +5,8 @@ const is_zero = require("./is_zero.js");
 const eulers_number = require("./eulers_number.js");
 const pow = require("./pow.js");
 
-function exp(power, { max_decimal_digits } = {}) {
-  const e = eulers_number(100);
+function exp(power, { max_decimal_digits = 100 } = {}) {
+  const e = eulers_number({ max_decimal_digits: 2 * max_decimal_digits });
 
   if (is_negative_infinity(power)) return "0";
   if (is_positive_infinity(power)) return "Infinity";

package.json

@@ -56,6 +56,7 @@
     "round_last_decimal.js",
     "sign.js",
     "sign_nonzero.js",
+    "softmax.js",
     "sort.js",
     "square_root.js",
     "subtract.js",

preciso.js

@@ -44,6 +44,8 @@ const root = require("./root.js");
 const root_integer_digits = require("./root_integer_digits.js");
 const round_last_decimal = require("./round_last_decimal.js");
 
+const softmax = require("./softmax.js");
+
 const square_root = require("./square_root.js");
 const subtract = require("./subtract.js");
 const long_subtraction = require("./long_subtraction.js");
@@ -128,6 +130,7 @@ const module_exports = {
   sign,
   sign_nonzero,
 
+  softmax,
   sort,
 
   sum,

softmax.js

@@ -0,0 +1,16 @@
+"use strict";
+
+const divide = require("./divide.js");
+const exp = require("./exp.js");
+const sum = require("./sum.js");
+
+function softmax(vector, { max_decimal_digits }) {
+  vector = vector.map(n => exp(n, { max_decimal_digits }));
+
+  const total = sum(vector);
+
+  return vector.map(n => divide(n, total, { max_decimal_digits, ellipsis: false }));
+}
+
+module.exports = softmax;
+module.exports.default = softmax;

test.js

@@ -45,6 +45,7 @@ const {
   round,
   round_last_decimal,
   sign,
+  softmax,
   sort,
   square_root,
   sum,
@@ -54,6 +55,12 @@ const {
 
 // const nthroot = (radicand, root) => Math.pow(radicand, 1 / root);
 
+test("softmax", ({ eq }) => {
+  const actual = ["1", "2", "3", "4", "1", "2", "3"];
+  const expected = ["0.02364054", "0.06426166", "0.1746813", "0.474833", "0.02364054", "0.06426166", "0.1746813"];
+  eq(softmax(actual, { max_decimal_digits: 8 }), expected);
+});
+
 test("root", ({ eq }) => {
   eq(root("-9", "1"), "-9");
   eq(root("-9", "2"), "3i");