數值與數學模組
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The modules described in this chapter provide numeric and math-related
functions and data types. The "numbers" module defines an abstract
hierarchy of numeric types. The "math" and "cmath" modules contain
various mathematical functions for floating-point and complex numbers.
The "decimal" module supports exact representations of decimal
numbers, using arbitrary precision arithmetic.

The following modules are documented in this chapter:

* "numbers" --- 數值的抽象基底類別

  * 數值的階層

  * 給型別實作者的註記

    * 加入更多數值 ABC

    * 實作算術操作

* "math" --- 數學函式

  * Number-theoretic and representation functions

  * Power and logarithmic functions

  * Trigonometric functions

  * Angular conversion

  * Hyperbolic functions

  * Special functions

  * 常數

* "cmath" --- Mathematical functions for complex numbers

  * Conversions to and from polar coordinates

  * Power and logarithmic functions

  * Trigonometric functions

  * Hyperbolic functions

  * Classification functions

  * 常數

* "decimal" --- Decimal fixed point and floating point arithmetic

  * Quick-start Tutorial

  * Decimal objects

    * Logical operands

  * Context objects

  * 常數

  * Rounding modes

  * Signals

  * Floating Point Notes

    * Mitigating round-off error with increased precision

    * Special values

  * Working with threads

  * Recipes

  * Decimal FAQ

* "fractions" --- Rational numbers

* "random" --- 生成偽隨機數

  * 簿記函式 (bookkeeping functions)

  * 回傳位元組的函式

  * 回傳整數的函式

  * 回傳序列的函式

  * 實數分布

  * 替代產生器

  * 關於 Reproducibility（復現性）的注意事項

  * 範例

  * 使用方案

* "statistics" --- 數學統計函式

  * 平均值與中央位置量數

  * 離度 (spread) 的測量

  * 兩個輸入之間的關係統計

  * 函式細節

  * 例外

  * "NormalDist" 物件

    * "NormalDist" 範例與錦囊妙計
