Calculation

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doubling in the context of our discussion

doubling in the context of our discussion

Yes.

I wasn't there, of course, but I can't imagine the people who designed this gauge system to base it on 2.00503151950125:1. They based it on 2 unless they were masochists or had http://en.wikipedia.org/wiki/Obsessive-compulsive_disorder

I'd think if, in the answer, you need more than 3 "significant figures" (not the same as decimal places) you've gone off the track somewhere.
Intermediate calculations are supposed to carry two more than the final answer (so, 5, in this case).

When you reverse engineer what comes out of some of these systems and tables, you get all kinds of strange stuff due to rounding errors and who knows what all else.
And sometimes with some stuff you cannot at all get back to what they were thinking. It's just gone. And sometimes they just did it because the boss said so.
 
Lxnxjxhx said:
...I wasn't there, of course, but I can't imagine the people who designed this gauge system to base it on 2.00503151950125:1. They based it on 2...
Click to expand...
The formula is actually Diameter in inches = 0.005*92^(36-n/39), where n is the AWG gauge number.

I'd think if, in the answer, you need more than 3 "significant figures" (not the same as decimal places) you've gone off the track somewhere.
Intermediate calculations are supposed to carry two more than the final answer (so, 5, in this case).
Click to expand...
While I believe significant figure rules have their place, I don't believe the rules should be used in all cases. I consider them more of a guideline than a rule. After all, you must consider those rules were put into practice back when people had to use a slide rule or such to calculate results.
 
rules, guidelines

rules, guidelines

http://en.wikipedia.org/wiki/Significant_figures

3 x PI = 9
3.000 x PI = 9.425
500 could be 5 x 10^2 (1 sign fig) or 5.00 x 10^2 (3 sign fig).

Reporting my weight as 183.457 pounds, even if it were known to that precision, implies a constancy that isn't there.

The speed of light probably should be reported as 299,792,458 metres per second because the people who use it probably need that many significant figures.

Hardly anyone observes this, though. I guess it still is important, somewhere.
 
Smart $ said:
The formula is actually Diameter in inches = 0.005*92^(36-n/39), where n is the AWG gauge number.
Click to expand...
That looks handy. Where did it come from?
Smart $ said:
While I believe significant figure rules have their place, I don't believe the rules should be used in all cases. I consider them more of a guideline than a rule. After all, you must consider those rules were put into practice back when people had to use a slide rule or such to calculate results.
Click to expand...
I remember one professor had us to use 3 significant digits unless the number started with a one, and then we were to use 4 significant digits. I don't know why. I would have thought you might want more digits if the number started with a five.
 
That formula looks something like that for calculating resistor values, probably gives equal spacing on a log scale.

Here's another one based on whatever 2 really is:
A = resistance of wire AWG C (say C = #30)
B = resistance of wire AWG D (say D = #27)
Then, B = Ax2^[(C-D)/3]
Inversely, C-D = 3[(log{b/a})/(log 2)]

And if you believe in the http://en.wikipedia.org/wiki/Butterfly_effect
you should carry many, many significant figures.
 
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