[討論] 有關有效位數
今天有人問我就交代一下,
首先都先把數據變成科學記號, 這是方便運算有效位數
以下說明都是直接舉例, 希望大家再舉一反三
加減法:
1.362 X 10^-4
3.111 X 10^-4
+
_____________________
4.473 X 10^-4
5.345
+ 6.728
____________________
12.073
7.26 X 10^14
- 6.69 X 10^14
-------------------
0.57 X 10^14
乘除:
3.26 X 10^-5 兩位
X 1.78 兩位
______________________
5.80 X 10^-5 兩位
4.3179 X 10^12
X 3.6 X 10^-19 兩位
_____________________
1.6 X 10^-6 去二位
34.60
/ 2.46287
_________________
14.05
log :
log(339) = 2.530 2 is called characteristic. 0.530 is called Mantissa.
log(3.39x10^-5) = -4.470
log(5.403x10^-8) = -7.2674
看得出規律? 339 是三位有效, 所以小數就取三位
5.403 是四位有效 所以小數取四位
聰明的物理系們, 10^2.531, 10^2.530, 10^2.529可以看出怎麼去位數吧?
340 339 338
講這麼多給個習題練習一下
log(0.001237)
log(1237)
10^4.37
做对有獎
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