有ISO的方法吗？ISO的修约方法是不同的

I cannot find the relevant ISO, but there is a brief description of the concerned subject on Page 235 of “The metrology handbook, by Jay L. Bucher” : ( http://books.google.com.hk/books?id=GFnjavm90EUC&pg=PA235&lpg=PA235&dq=ISO,+rounding&source=bl&ots=WGuOgfs2YI&sig=oqioQq4Rf9aK8gPZiPeq9AeuW-k&hl=zh-CN#v=onepage&q=ISO%2C%20rounding&f=false )







The above examples also indicate that the first thing first is to decide whether the rounding is based on N significant digits or N decimal places.

= = = = = =

Discussion :

In the Example 5 above, should the Floor(0.623, 0.25) be 0.5 ?

Should be 0.5! Tried with MS Excel!

I just learnt from your post above that there is really a function for =Floor(0.623, 0.25) in Excel

本想写一篇有关有効数字/修约/合格判定的帖, 但最近有兼职, 家里又装修, 没时间了。 现将收集了的有关标准上载与大家分享。

(BS1957是一个已作废的标准, 但其解释严谨, 可作参考。 个人觉得GBT8170简明全面, 但要耐心细心学习, 往往隔一段时间后再学一遍, 又有新体会。)

Just found that there are many other rounding methods :
(From http://en.wikipedia.org/wiki/Rounding )

1 Types of rounding
2 Rounding to a specified increment
3 Rounding to integer
4 Tie-breaking
4.1 Round half up
4.2 Round half down
4.3 Round half away from zero
4.4 Round half towards zero
4.5 Round half to even
4.6 Round half to odd
4.7 Stochastic rounding
4.8 Alternating tie-breaking
5 Dithering and error diffusion
6 Rounding to simple fractions
7 Scaled rounding
8 Round to available value
9 Floating-point rounding
10 Double rounding
11 Exact computation with rounded arithmetic
12 The table-maker's dilemma
13 History
14 Rounding functions in programming languages
15 Other rounding standards
15.1 U.S. Weather Observations
15.2 Negative zero in meteorology
16 See also
17 External links
18 References

真真觉得是技术贴啊，值得长时间研究回顾。