Talk:Significance arithmetic
From Wikipedia, the free encyclopedia
Contents |
[edit] Precise numbers vs. sig. fig.
The number of significant figures in the number "8" is actually infinite. The number "8." has only one significant figure.
- No, they both have just the one. A decimal point which is not followed by some other digit is irrelevant (especially in this font, where it might just be the period ending a sentence). quota
So, technically, 8 x 8 is 64, whereas 8. x 8. is 60.
- technically???!
Remember, 8., 8, and 08 all have one significant figure, wherease 8.0 has 2.
- OK.
"8", by itself, doesn't have infinite significant figures. You need to know how that number was obtained -- if it was measured, then it has 1 significant figure, if it was counted, then it has an infinite number (if you want to call it that) of significant digits. The obtaining of the number is what's important -- i.e. If I counted 8 matches in each matchbook, and I counted that I have 8 matchbooks, then 8 * 8 = 64! However, if I measured that each candle is 8 cm (to 1 significant digit) long, then if I have 8 candles, 8 * 8 = 6 decimeter of candle, because I only know the measurement to 1 significant digit. When you have a counted number, it has no effect on the number of significant figures you carry. The use of the period after the number is only a convention.
[edit] speed of light
Is the speed of light really a defined physical constant with infinite significant figures? Isn't it simply a measured constant, and therefore have significant figures? Tejastheory 03:25, 31 August 2005 (UTC)
- I agree, the speed of light is definitely a bad example.
- Also Banker's rounding is most useful when the quantities are exact, but with just a few significant figures more than wanted, such as currency. Generally, a large number of values are more likely to average out any bias, so that's also a misleading statement. Mark Hurd 19:31, 23 September 2005 (UTC)
- The speed of light in a vacuum is defined to be 299,792,458 metres per second. --Apoc2400 06:22, 17 November 2005 (UTC)
- Speed of light is a constant, but it's still a measured constant. In a lot of physics, 3x10^8 is simply used, yet 3x10^8 does not have infinite significant figures - it is only precise to one significant figure. 07:03, 17 November 2005 (UTC)
- The speed of light in a vacuum is defined to be 299,792,458 metres per second. --Apoc2400 06:22, 17 November 2005 (UTC)
[edit] 100 has one sig. fig.
The part about adding and subtracting sig figs is wrong at the part where it says:
- 100 + 110 = 210
-
- 100, 110 are significant up to the ones place, even though these digits are zeroes. So will the answer.
100 has 1 sig fig, and 110 has 2, therefore the answer would technically be 200. In order to do what they are saying you would have to do 1.00E2 + 1.10E2 = 2.10E2
- I changed 210 to 200, added an example that does add to 210, and clarified some of the prose. Redhookesb 07:33, 31 July 2007 (UTC)
[edit] rant
This article offers opinions without clarifying that they are. I agree that significant arithmetic is a bit crazy, but isn't this an encyclopedia?
Also, I'd like to suggest making a seperate article for significant digits instead of having it redirect here. I might do it if I have time.
Cheers,
Forezt 23:05, 30 September 2006 (UTC)
- I agree. This article is a bit of rant. It would be better to have a clear concise explanation of signicance arithmetic with a note about problems. User:Winterstein 1st November 2006
-
- I just noticed the comment above after redirecting the "significant figures" article here. It seems we've been around this same block very recently. However, please explain why we need a separate article? --Slashme 16:50, 9 December 2006 (UTC)
- Word. The inexplicably bitter tone of the now defunct entry on Significant Figures has now snuck into this otherwise promising page, under the "Uncertainty and Error" section. Significance arithmetic obviously has its limitations, but these limitations can certainly be addressed in a more measured tone. In addition, the section claims that "propagation of uncertainty" is the putative topic of the article. To the contrary, the article itself contains the text, "See the article on propagation of uncertainty for these more advanced and precise rules." It seems ungood to have an entry at variance with itself. This entry seems to need a unified explanation of the relationship between truly correct principles of uncertainty-reporting and all imperfect methods of uncertainty approximation. Right now, it's Correct Method Plus Some Approximation Methods on the one side, versus Evil Sig Figs on the other.
ben.mcclure 15:10, 11 December 2006 (UTC)
- I think the old article was simpler, clearer, and more helpful than this one. I think it should be brought back. Redhookesb 07:36, 31 July 2007 (UTC)
- I changed the uncertainty section a bit to try to reduce (ha ha) the uncertainty it likely introduces in the reader. Jon the Geek (talk) 17:20, 22 January 2008 (UTC)
[edit] Broken link(s)
I removed the following from the article:
example: bean counting)
I'd be interested to know what that was, but the link is dead. --Slashme 16:42, 9 December 2006 (UTC)
- It works for me. It should be put back in. --Djsonik 03:05, 20 December 2006 (UTC)
[edit] Re-merge with Significant Figures?
It seems to me that most people searching for "significant figures" (or "significant digits") would like both the (relevant) information from that article, plus the information in this article. I plan to merge them together soon, with a substantial cleanup (and probably expansion), including pushing all of the (mostly beyond-the-scope of this article) dissenting views about the usefulness of sig figs into a section much like I did here yesterday. Any objections? Jon the Geek (talk) 16:12, 23 January 2008 (UTC)
[edit] Using "error" to mean "mistake".
In colloquial English, "error" is a synonym for a mistake. Let's try to avoid that usage here. Bkalafut (talk) 21:26, 5 June 2008 (UTC)
