round函数

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请问round函数是什么意思，谢谢了

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关键词：ROUND und 是什么意思

四舍五入函数

进来看看

洁宝宝记得幸福 发表于 2015-7-27 16:30
四舍五入函数

怎么个舍法怎么个如法，请大神能不能说清楚，为什么有时候四舍五入，有时候五也舍去呢

Nelsh--Deng 发表于 2015-7-27 17:27
怎么个舍法怎么个如法，请大神能不能说清楚，为什么有时候四舍五入，有时候五也舍去呢

是不是四舍六入五成双？以前学分析化学的时候用的规则

飞行员 发表于 2015-7-27 23:04
是不是四舍六入五成双？以前学分析化学的时候用的规则

这个还真不知道

飞行员 发表于 2015-7-27 23:04
是不是四舍六入五成双？以前学分析化学的时候用的规则

博学，不错

66666666

Both round() and signif() round numbers to the nearest possibility. So, if the first digit that’s dropped is smaller than 5, the number is rounded down. If it’s bigger than 5, the number is rounded up.

If the first digit that is dropped is exactly 5, R uses a rule that’s common in programming languages: Always round to the nearest even number. round(1.5) and round(2.5) both return 2, for example, and round(-4.5) returns -4.

Contrary to round(), three other functions always round in the same direction:

floor(x) rounds to the nearest integer that’s smaller than x. So floor(123.45) becomes 123 and floor(-123.45) becomes –124.

ceiling(x) rounds to the nearest integer that’s larger than x. This means ceiling (123.45) becomes 124 and ceiling(123.45) becomes –123.

trunc(x) rounds to the nearest integer in the direction of 0. So trunc(123.65) becomes 123 and trunc(-123.65) becomes –123.

Note that for rounding off a 5, the IEC 60559 standard is expected to be used, ‘go to the even digit’. Therefore round(0.5) is 0 and round(-1.5) is -2. However, this is dependent on OS services and on representation error (since e.g. 0.15 is not represented exactly, the rounding rule applies to the represented number and not to the printed number, and so round(0.15, 1) could be either 0.1 or 0.2).

Rounding to a negative number of digits means rounding to a power of ten, so for example round(x, digits = -2) rounds to the nearest hundred.

For signif the recognized values of digits are 1...22, and non-missing values are rounded to the nearest integer in that range. Complex numbers are rounded to retain the specified number of digits in the larger of the components. Each element of the vector is rounded individually, unlike printing.