---
title: "数学 Math"
description: "位标志、随机挑选与浮点四则"
---
---
title: 数学 Math
description: 位标志、随机挑选与浮点四则
---
`sa` · 扩展 `math` · 需对应 CLEO 扩展
位标志、随机挑选、浮点四则。
写法见 [Lua](/docs/cleo/syntax) / [Redux](/docs/cleo/syntax-redux)。
## 测位
整数第 `bitIndex` 位（0–31）是否为 1。用在 `if` 里。
```text
2700 IS_BIT_SET
in: number, bitIndex
```
```lua
if isBitSet(flags, 3) then
end
```
```js
if (Math.isBitSet(number, bitIndex)) {
}
```
## 置位
把变量某位置 1。
```text
2701 SET_BIT
in: number, bitIndex
```
```lua
setBit(flags, 3)
```
```js
Math.setBit(number, bitIndex)
```
## 清位
把变量某位清 0。
```text
2702 CLEAR_BIT
in: number, bitIndex
```
```lua
clearBit(flags, 3)
```
```js
Math.clearBit(number, bitIndex)
```
## 设/清位
按 `state` 设 / 清某位。
```text
2703 TOGGLE_BIT
in: number, bitIndex, state
```
```lua
toggleBit(flags, 3, true)
```
```js
Math.toggleBit(number, bitIndex, state)
```
## 真值判断
值是否“真”（非 0 / 非空串）。用在 `if` 里。
```text
2704 IS_TRUTHY
in: value
```
```lua
if isTruthy(v) then
end
```
```js
if (Math.isTruthy(value)) {
}
```
## 随机挑整数
从参数列表里随机挑一个整数。
```text
2705 PICK_RANDOM_INT
in: values...
out: result
```
```lua
local r = pickRandomInt(1, 2, 3, 4)
```
```js
const result = Math.randomPick(...values)
```
## 随机挑浮点
```text
2706 PICK_RANDOM_FLOAT
in: values...
out: result
```
```lua
local r = pickRandomFloat(0.5, 1.0, 1.5)
```
```js
const result = native("PICK_RANDOM_FLOAT", ...values)
```
## 随机挑字符串
```text
2707 PICK_RANDOM_TEXT
in: values...
out: result
```
```lua
local r = pickRandomText("a", "b", "c")
```
```js
const result = native("PICK_RANDOM_TEXT", ...values)
```
## 百分比概率
以 `percent`%（0–100）概率为真。用在 `if` 里。
```text
2708 RANDOM_CHANCE
in: percent
```
```lua
if randomChance(25.0) then
end
```
```js
if (Math.randomChance(percent)) {
}
```
## 浮点加
```text
2709 FLOAT_ADD
in: a, b
out: result
```
```lua
local r = floatAdd(a, b)
```
```js
const result = native("FLOAT_ADD", a, b)
```
## 浮点减
```text
270A FLOAT_SUB
in: a, b
out: result
```
```lua
local r = floatSub(a, b)
```
```js
const result = native("FLOAT_SUB", a, b)
```
## 浮点乘
```text
270B FLOAT_MUL
in: a, b
out: result
```
```lua
local r = floatMul(a, b)
```
```js
const result = native("FLOAT_MUL", a, b)
```
## 浮点除
```text
270C FLOAT_DIV
in: a, b
out: result
```
```lua
local r = floatDiv(a, b)
```
```js
const result = native("FLOAT_DIV", a, b)
```