INCH CHART BY 128ths

[koenbro]

Pi is fun.

Some argu about accuracy when calculations done.

When we built spreadsheets or debase calculations we never used pi as it limited the accuracy to whatever it was.

Instead, we would multiply by 22 then divide by 7.

Sometimes it came out even.

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What application was that?
22/7 is a very crude approximation.


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[Jake M]

Looking at that I am so glad we are metric

I'll have you know that 7/128 of the world's population still uses imperial measurements. That many metrological luddites can't be wrong.

 

[savarin]

I think the more accurate number is 3/195's or to put it another way 1/65th

 

[stupoty]

I got this real nice caliper from ebay today with a massively big easy read metric vernier and also ! An imperial side.



Stu

 

[tq60]

What application was that?
22/7 is a very crude approximation.


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Back in the day we were learning programming C+ while manning the IRS data system, we were there to repair terminals as they failed.

Lots of idle time.

Had a book on scratch building model helicopters so created a chopper cad program.

Entered weights, motor hp. Dimensions of every moving part and the math would calculate a bunch of things to output lift and direction of flight.

Pi is 22/7 exactly, limiting the Decimal point or using a predefined number is the approximation.

We experimented with using both and it would make minor differences in both calculating speed and outcome.

Yes, we had a lot of time on our hands.

Never was able to get past the table of outcomes to connect to graphics for visual output.

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[pontiac428]

I find myself constantly referring to my Starrett chart, it is as useful as a a 6" caliper on a daily basis. But the ultimate "chart" for splitting hairs will always be one of these 1985 MetCon conversion calculators. Of course, a dime store solar calc works great for dividing by 128.

Isn't it common for the calipers with fractional vernier to have 128th's so you can measure any fraction from that (i.e. 1/64 = 2/128 , 1/8 = 16/128)

Stu

By using the vernier like that, you are basically using it as a slide rule.

 

[Parlo]

Back in the day we were learning programming C+ while manning the IRS data system, we were there to repair terminals as they failed.

Lots of idle time.

Had a book on scratch building model helicopters so created a chopper cad program.

Entered weights, motor hp. Dimensions of every moving part and the math would calculate a bunch of things to output lift and direction of flight.

Pi is 22/7 exactly, limiting the Decimal point or using a predefined number is the approximation.

We experimented with using both and it would make minor differences in both calculating speed and outcome.

Yes, we had a lot of time on our hands.

Never was able to get past the table of outcomes to connect to graphics for visual output.

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Please research this. 22/7 is a fractional estimation, not exactly right. If you find pi on any calculator it is not the decimal of 22/7 if the fraction is exact then all calculators are wrong.

 

[Jake M]

Pi is 22/7 exactly, limiting the Decimal point or using a predefined number is the approximation.

While it's plenty good enough for nearly anything I'd use it for, that's not the case.

Pi is known (to science, not to me) to something like 50 trillion digits. 3.14159(etc)

22/7 is only good to three significant figures, it deviates on the fourth.

 

[Bi11Hudson]

Disagreed: The fraction deviates on the third decimal place. That from the calculator that comes on WinDoze 10.

.

 

[stupoty]

Disagreed: The fraction deviates on the third decimal place. That from the calculator that comes on WinDoze 10.

.

You could check it against one mile of Pi

Stu