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RealDigits

Usage

RealDigits[x] 给出近似实数x中的数字构成的阵列,和小数点左边的数位个数.
RealDigits[x, b]给出x中一列以b为基底的数字.
RealDigits[x, b, len] 给出 len 个数位的列表.
RealDigits[x, b, len, n] 给出以 的系数开始的len个数位.


Notes

RealDigits[x] 通常返回一个长度等于Precision[x]的数字列表.
RealDigits[x]RealDigits[x, b] 通常要求 x 是一个由,举例来讲,N返回的近似实数. RealDigits[x, b, len] 也适用于精确数.
• 对于一个精确的有理数,RealDigits[x]返回一个形如  ,  , ... ,   ,  , ...   的数字列表,表示数字  的无限循环跟随.
• 如果 len 大于 Log[10, b] Precision[x]剩下的数字以Indeterminate填充.
RealDigits[x, b, len, n] 的系数开始,并在必要时用0截断或填充.
RealDigits[x, b, len, -1]x中紧挨以b为基底的小数点右边的数字开始.
RealDigits[x, b]中的基底b不必是整数.对使得 的任意实数b , RealDigits[x, b]连续找到b的幂的最大整数倍使得当得到一个非负余项时可以被去掉.
RealDigits[x] 不考虑 x 的符号.
FromDigits可以被用作RealDigits的逆.
• 参见Mathematica 全书: 3.1.3节.
Further Examples

Here is an approximation to  .

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This gives the individual digits as a list. The  at the end means that there are  digits to the left of the decimal point.

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As an exact fraction,  has a repeating part.

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Here is an approximate number.

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Here are its digits. The  at the end means that there are  digits to the left of the decimal point.

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RealDigits returns a list of digits whose length is equal to the number's precision.

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Similarly, these are its digits in base  . There are  digits in all.

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 digits in base  is  digits in base  .

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Here is an exact number.

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This shows the first  digits of n in base  .The total number of digits is  .

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This gives the first  digits starting with the coefficient of  . There are  digits counting from that coefficient.

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