From ef2631f77fe431da712595d18b3a970fdfffdb19 Mon Sep 17 00:00:00 2001
From: Jos de Jong <wjosdejong@gmail.com>
Date: Thu, 18 Aug 2022 12:05:04 +0200
Subject: [PATCH] Try out performance of dependency injection on individual
 function signatures (see #1975)

---
 test/benchmark/dependency_injection.js | 87 ++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 test/benchmark/dependency_injection.js

diff --git a/test/benchmark/dependency_injection.js b/test/benchmark/dependency_injection.js
new file mode 100644
index 0000000000..a683c96d2a
--- /dev/null
+++ b/test/benchmark/dependency_injection.js
@@ -0,0 +1,87 @@
+const Benchmark = require('benchmark')
+const { create, factory, isComplex } = require('../../lib/cjs/index.js')
+const { flatten } = require('../../lib/cjs/utils/array.js')
+const { all } = require('../../lib/cjs/index.js')
+
+// In this benchmark we verify whether injecting dependencies on every individual function signature
+// has an impact on the performance, since this is the approach that pocomath takes
+//
+// Benchmark result:
+// both have the same performance, so there is no noticeable difference
+// this is indeed what I would expect: this is something the JS engine can optimize on,
+// it is still a bunch of references to functions passed via function arguments
+
+const math = create(all)
+
+const name = 'hypot2'
+const dependencies = ['typed', 'abs', 'addScalar', 'divideScalar', 'multiplyScalar', 'sqrt', 'smaller', 'isPositive']
+const createHypot2 = factory(name, dependencies, (deps) => {
+  // in hypot2 we resolve the dependencies on every individual signature
+  function resolve (fn) {
+    return fn(deps)
+  }
+
+  return deps.typed(name, {
+    '... number | BigNumber': resolve(_createHypot),
+
+    Array: resolve(_createHypot),
+
+    Matrix: resolve(deps => {
+      const hypot = _createHypot(deps)
+
+      return M => hypot((flatten(M.toArray())))
+    })
+  })
+
+  function _createHypot ({ abs, addScalar, divideScalar, multiplyScalar, sqrt, smaller, isPositive }) {
+    /**
+     * Calculate the hypotenusa for an Array with values
+     * @param {Array.<number | BigNumber>} args
+     * @return {number | BigNumber} Returns the result
+     * @private
+     */
+    return function _hypot (args) {
+      // code based on `hypot` from es6-shim:
+      // https://github.com/paulmillr/es6-shim/blob/master/es6-shim.js#L1619-L1633
+      let result = 0
+      let largest = 0
+
+      for (let i = 0; i < args.length; i++) {
+        if (isComplex(args[i])) {
+          throw new TypeError('Unexpected type of argument to hypot')
+        }
+        const value = abs(args[i])
+        if (smaller(largest, value)) {
+          result = multiplyScalar(result,
+            multiplyScalar(divideScalar(largest, value), divideScalar(largest, value)))
+          result = addScalar(result, 1)
+          largest = value
+        } else {
+          result = addScalar(result, isPositive(value)
+            ? multiplyScalar(divideScalar(value, largest), divideScalar(value, largest))
+            : value)
+        }
+      }
+
+      return multiplyScalar(largest, sqrt(result))
+    }
+  }
+})
+math.import(createHypot2)
+
+const values = [3, 4, 5, 6, 7]
+
+const suite = new Benchmark.Suite()
+suite
+  .add('hypot original (dependency injection on the whole function)', function () {
+    math.hypot(values)
+  })
+  .add('hypot2 (dependency injection per signature)', function () {
+    math.hypot2(values)
+  })
+  .on('cycle', function (event) {
+    console.log(String(event.target))
+  })
+  .on('complete', function () {
+  })
+  .run()