From 220cf9cf9bab124b30436a2ecaf4a5c55936652b Mon Sep 17 00:00:00 2001
From: Anthony Fu <anthonyfu117@hotmail.com>
Date: Sun, 17 Jul 2022 15:22:40 +0800
Subject: [PATCH 1/2] feat(useMath): new function

---
 packages/math/useMath/index.md      | 24 ++++++++++++++++++++++++
 packages/math/useMath/index.test.ts | 29 +++++++++++++++++++++++++++++
 packages/math/useMath/index.ts      | 16 ++++++++++++++++
 packages/shared/utils/types.ts      |  2 ++
 4 files changed, 71 insertions(+)
 create mode 100644 packages/math/useMath/index.md
 create mode 100644 packages/math/useMath/index.test.ts
 create mode 100644 packages/math/useMath/index.ts

diff --git a/packages/math/useMath/index.md b/packages/math/useMath/index.md
new file mode 100644
index 00000000000..0f5fad0b2be
--- /dev/null
+++ b/packages/math/useMath/index.md
@@ -0,0 +1,24 @@
+---
+category: '@Math'
+---
+
+# useMath
+
+Reactive `Math` methods.
+
+## Usage
+
+```ts
+import { useMath } from '@vueuse/math'
+
+const base = ref(2)
+const exponent = ref(3)
+const result = useMath('pow', base, exponent) // Ref<8>
+
+const num = ref(2)
+const root = useMath('sqrt', num) // Ref<1.4142135623730951>
+
+num.value = 4
+console.log(root.value) // 2.8284271247461903
+```
+```
diff --git a/packages/math/useMath/index.test.ts b/packages/math/useMath/index.test.ts
new file mode 100644
index 00000000000..766e9970e17
--- /dev/null
+++ b/packages/math/useMath/index.test.ts
@@ -0,0 +1,29 @@
+import { ref } from 'vue-demi'
+import { useMath } from '.'
+
+describe('useMath', () => {
+  it('should be defined', () => {
+    expect(useMath).toBeDefined()
+  })
+
+  it('should accept numbers', () => {
+    const v = useMath('pow', 2, 3)
+    expect(v.value).toBe(8)
+  })
+
+  it('should accept refs', () => {
+    const base = ref(2)
+    const exponent = ref(3)
+    const result = useMath('pow', base, exponent)
+
+    expect(result.value).toBe(8)
+
+    const num = ref(4)
+    const root = useMath('sqrt', num)
+
+    expect(root.value).toBe(2)
+
+    num.value = 16
+    expect(root.value).toBe(4)
+  })
+})
diff --git a/packages/math/useMath/index.ts b/packages/math/useMath/index.ts
new file mode 100644
index 00000000000..ce79546b146
--- /dev/null
+++ b/packages/math/useMath/index.ts
@@ -0,0 +1,16 @@
+import type { ArgumentsType, Reactified } from '@vueuse/shared'
+import { reactify } from '@vueuse/shared'
+
+export type UseMathKeys = keyof { [K in keyof Math as Math[K] extends (...args: any) => any ? K : never]: unknown }
+
+/**
+ * Reactive `Math` methods.
+ *
+ * @see https://vueuse.org/useMath
+ */
+export function useMath<K extends keyof Math>(
+  key: K,
+  ...args: ArgumentsType<Reactified<Math[K], true>>
+): ReturnType<Reactified<Math[K], true>> {
+  return reactify(Math[key] as any)(...args) as any
+}
diff --git a/packages/shared/utils/types.ts b/packages/shared/utils/types.ts
index 92dd3ecdade..daabeaf9fa2 100644
--- a/packages/shared/utils/types.ts
+++ b/packages/shared/utils/types.ts
@@ -62,6 +62,8 @@ export type ShallowUnwrapRef<T> = T extends Ref<infer P> ? P : T
 
 export type Awaitable<T> = Promise<T> | T
 
+export type ArgumentsType<T> = T extends (...args: infer U) => any ? U : never
+
 export interface Pausable {
   /**
    * A ref indicate whether a pusable instance is active

From 4a774d17719dc1783ad8c007e2e9d55e3e23ebc7 Mon Sep 17 00:00:00 2001
From: Anthony Fu <anthonyfu117@hotmail.com>
Date: Sun, 17 Jul 2022 15:24:45 +0800
Subject: [PATCH 2/2] chore: update

---
 packages/math/useMath/index.md | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/math/useMath/index.md b/packages/math/useMath/index.md
index 0f5fad0b2be..dfc44e842e2 100644
--- a/packages/math/useMath/index.md
+++ b/packages/math/useMath/index.md
@@ -19,6 +19,5 @@ const num = ref(2)
 const root = useMath('sqrt', num) // Ref<1.4142135623730951>
 
 num.value = 4
-console.log(root.value) // 2.8284271247461903
-```
+console.log(root.value) // 2
 ```