From a131845524812c2117197cbfcbc8e054f8b73a24 Mon Sep 17 00:00:00 2001
From: David Contreras <dvd.cnt@gmail.com>
Date: Thu, 25 Jan 2024 08:27:42 -0600
Subject: [PATCH] change isZero to take epsilon into account

---
 src/function/utils/isZero.js                  | 19 ++++---------------
 test/unit-tests/function/utils/isZero.test.js | 10 ++++++++++
 2 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/src/function/utils/isZero.js b/src/function/utils/isZero.js
index 4134200dc8..65131eb4e3 100644
--- a/src/function/utils/isZero.js
+++ b/src/function/utils/isZero.js
@@ -1,11 +1,10 @@
 import { deepMap } from '../../utils/collection.js'
 import { factory } from '../../utils/factory.js'
-import { isZeroNumber } from '../../plain/number/index.js'
 
 const name = 'isZero'
-const dependencies = ['typed']
+const dependencies = ['typed', 'equalScalar']
 
-export const createIsZero = /* #__PURE__ */ factory(name, dependencies, ({ typed }) => {
+export const createIsZero = /* #__PURE__ */ factory(name, dependencies, ({ typed, equalScalar }) => {
   /**
    * Test whether a value is zero.
    * The function can check for zero for types `number`, `BigNumber`, `Fraction`,
@@ -40,18 +39,8 @@ export const createIsZero = /* #__PURE__ */ factory(name, dependencies, ({ typed
    *                    Throws an error in case of an unknown data type.
    */
   return typed(name, {
-    number: isZeroNumber,
-
-    BigNumber: function (x) {
-      return x.isZero()
-    },
-
-    Complex: function (x) {
-      return x.re === 0 && x.im === 0
-    },
-
-    Fraction: function (x) {
-      return x.d === 1 && x.n === 0
+    'number | BigNumber | Complex | Fraction': function (x) {
+      return equalScalar(x, 0)
     },
 
     Unit: typed.referToSelf(self =>
diff --git a/test/unit-tests/function/utils/isZero.test.js b/test/unit-tests/function/utils/isZero.test.js
index 6e1f7dd4d5..da9b4593a5 100644
--- a/test/unit-tests/function/utils/isZero.test.js
+++ b/test/unit-tests/function/utils/isZero.test.js
@@ -19,6 +19,16 @@ describe('isZero', function () {
     assert.strictEqual(isZero(NaN), false)
   })
 
+  it('should test whether a number is almost zero', function () {
+    const mymath = math.create()
+    assert.strictEqual(mymath.isZero(1e-16), true)
+    assert.strictEqual(mymath.isZero(1e-2), false)
+    mymath.config({ epsilon: 1e-3 })
+    assert.strictEqual(mymath.isZero(1e-16), true)
+    // assert.strictEqual(mymath.isZero(1e-4), true)
+    // assert.strictEqual(mymath.isZero(1e-2), false)
+  })
+
   it('should test whether a boolean is zero', function () {
     assert.strictEqual(isZero(true), false)
     assert.strictEqual(isZero(false), true)