forked from xuos/xiuos
284 lines
4.3 KiB
Markdown
284 lines
4.3 KiB
Markdown
## **math** – 数学函数
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**math** 模块提供了对 C 标准定义的数学函数的访问。
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> 注意：本模块需要带有硬件 FPU，精度是32位，这个模块需要浮点功能支持。
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### 常数
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#### **math.e**
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自然对数的底数。
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示例：
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```
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>>>import math
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>>>print(math.e)
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2.718282
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```
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#### **math.pi**
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圆周长与直径的比值。
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示例：
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```
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>>> print(math.pi)
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3.141593
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```
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### 函数
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#### **math.acos(x)**
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传入弧度值，计算cos(x)的反三角函数。
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#### **math.acosh(x)**
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返回 ``x`` 的逆双曲余弦。
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#### **math.asin(x)**
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传入弧度值，计算sin(x)的反三角函数。
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示例：
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```
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>>> x = math.asin(0.5)
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>>> print(x)
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0.5235988
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```
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#### **math.asinh(x)**
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返回``x`` 的逆双曲正弦。
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#### **math.atan(x)**
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返回 ``x`` 的逆切线。
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#### **math.atan2(y, x)**
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Return the principal value of the inverse tangent of y/x.
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#### **math.atanh(x)**
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Return the inverse hyperbolic tangent of x.
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#### **math.ceil(x)**
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向上取整。
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示例：
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```
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>>> x = math.ceil(5.6454)
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>>> print(x)
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6
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```
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#### **math.copysign(x, y)**
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Return x with the sign of y.
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#### **math.cos(x)**
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传入弧度值，计算余弦。
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示例：计算cos60°
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```
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>>> math.cos(math.radians(60))
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0.5
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```
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#### **math.cosh(x)**
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Return the hyperbolic cosine of x.
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#### **math.degrees(x)**
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弧度转化为角度。
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示例：
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```
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>>> x = math.degrees(1.047198)
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>>> print(x)
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60.00002
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```
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#### **math.erf(x)**
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Return the error function of x.
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#### **math.erfc(x)**
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Return the complementary error function of x.
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#### **math.exp(x)**
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计算e的x次方（幂）。
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示例：
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```
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>>> x = math.exp(2)
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>>> print(x)
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7.389056
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```
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#### **math.expm1(x)**
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计算 math.exp(x) - 1。
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#### **math.fabs(x)**
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计算绝对值。
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示例：
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```
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>>> x = math.fabs(-5)
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>>> print(x)
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5.0
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>>> y = math.fabs(5.0)
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>>> print(y)
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5.0
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```
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#### **math.floor(x)**
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向下取整。
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示例：
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```
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>>> x = math.floor(2.99)
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>>> print(x)
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2
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>>> y = math.floor(-2.34)
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>>> print(y)
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-3
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```
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#### **math.fmod(x, y)**
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取x除以y的模。
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示例：
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```
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>>> x = math.fmod(4, 5)
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>>> print(x)
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4.0
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```
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#### **math.frexp(x)**
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Decomposes a floating-point number into its mantissa and exponent. The returned value is the tuple (m, e) such that x == m * 2**e exactly. If x == 0 then the function returns (0.0, 0), otherwise the relation 0.5 <= abs(m) < 1 holds.
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#### **math.gamma(x)**
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返回伽马函数。
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示例：
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```
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>>> x = math.gamma(5.21)
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>>> print(x)
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33.08715
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```
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#### **math.isfinite(x)**
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Return True if x is finite.
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#### **math.isinf(x)**
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Return True if x is infinite.
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#### **math.isnan(x)**
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Return True if x is not-a-number
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#### **math.ldexp(x, exp)**
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Return x * (2**exp).
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#### **math.lgamma(x)**
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返回伽马函数的自然对数。
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示例：
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```
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>>> x = math.lgamma(5.21)
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>>> print(x)
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3.499145
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```
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#### **math.log(x)**
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计算以e为底的x的对数。
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示例：
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```
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>>> x = math.log(10)
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>>> print(x)
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2.302585
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```
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#### **math.log10(x)**
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计算以10为底的x的对数。
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示例：
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```
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>>> x = math.log10(10)
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>>> print(x)
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1.0
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```
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#### **math.log2(x)**
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计算以2为底的x的对数。
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示例：
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```
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>>> x = math.log2(8)
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>>> print(x)
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3.0
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```
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#### **math.modf(x)**
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Return a tuple of two floats, being the fractional and integral parts of x. Both return values have the same sign as x.
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#### **math.pow(x, y)**
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计算 x 的 y 次方（幂）。
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示例：
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```
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>>> x = math.pow(2, 3)
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>>> print(x)
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8.0
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```
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#### **math.radians(x)**
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角度转化为弧度。
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示例：
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```
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>>> x = math.radians(60)
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>>> print(x)
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1.047198
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```
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#### **math.sin(x)**
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传入弧度值，计算正弦。
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示例：计算sin90°
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```
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>>> math.sin(math.radians(90))
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1.0
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```
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#### **math.sinh(x)**
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Return the hyperbolic sine of x.
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#### **math.sqrt(x)**
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计算平方根。
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示例：
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```
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>>> x = math.sqrt(9)
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>>> print(x)
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3.0
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```
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#### **math.tan(x)**
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传入弧度值，计算正切。
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示例：计算tan60°
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```
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>>> math.tan(math.radians(60))
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1.732051
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```
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#### **math.tanh(x)**
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Return the hyperbolic tangent of x.
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#### **math.trunc(x)**
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取整。
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示例：
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```
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>>> x = math.trunc(5.12)
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>>> print(x)
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5
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>>> y = math.trunc(-6.8)
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>>> print(y)
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-6
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```
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更多内容可参考 [math](http://docs.micropython.org/en/latest/pyboard/library/math.html) 。
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