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Steve Taranovich

Enjoy a slice of Pi Day

Steve Taranovich
Victor Lorenzo
Victor Lorenzo
3/18/2017 4:55:55 AM
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Blogger
Re: Pi Day
Pi Day celebration, I think, is for mathematicians like MAY-4th for Start Wars fans, I don't think it is universal.

In terms of units conversion I find more problematic the fact that several units share the same name, in the same language, and have different magnitudes when compared to other standard magnitudes. The most important point to take into account here is to be sure of the magnitude units we are working with.

How many digits should we use while converting from one unit to other? That depends on the final allowed error for the measurement or the control loop. I find very unconfortable working with mixed imperial/metric defined component footprints as it sometimes makes difficult to define the grid size for PCB routing.

The date/time representation format is another issue as you point. It is a big concern for me when developing Windows applications for runnind in different languages or different locales.It is of more importance when executing queries in databases. You can be working in two instanciations of the system using the same database engine release, and the same application release running on two different windows locales. Of course there are tricks for solving this issue, but you must be always aware that it can show up and create a big mess.

Some countries use the comma as the decimal separator (like Spain) and some others use the dot. And the opposite for the thousands separator. It is very dangerous if not taken properly into account too.

The same hapends when working with CNC machines. Are you generating G-Code in inches or millimeters? It is a common trap for newbies.

The solution? Be careful, very careful, and methodic, and take into account the amount of error allowed when doing conversions, and in programming terms, program defensively, and create a well structured and easy to follow documentation, always.

 

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Peter.Checkovich_#2
Peter.Checkovich_#2
3/16/2017 10:20:31 AM
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Newbie
Pi Day
Although Pi is universal across all mathematics, is Pi Day celebrated throughout the world?

The only country in the world that uses a M/D/Y format exclusively is the USA. The only other country to use it at all is Canada, which is somewhat schizophrenic due to its French and American-English backgrounds.

The vast majority of countries use some format that orders the time-period-markers in consecutive size-order of the time interval defined. This seems like a natural ordering, but the USA chooses a different ordering.

This leads to an issue that I have never seen a clearly explained. Many of us now communicate via email with others from around the world. Which ordering format should be used? Should the writer use that of the country he/she is a citizen of? Where he/she is currently located? The location of the recipient of the email? If recipients reside in more than one country, then what? For someone who replies to the initial email, should they stay with the initial ordering or switch to their local variant? If several Americans start an email thread using a M/D/Y format, and then someone decides that they want to send a reply and cc someone from Europe, should they go back and edit the previous thread-entries first?

There are similar issues that arise from variants of spelling of English words from around the world, but this is much less likely to create major confusion as a misundersting of dates. Also, using relative terms like yesterday, today or tomorrow can also lead to confusion, depending on the day it is where the sender/receiver are located.

Since the article also discusses the number of decimal places required for various applications, what guidelines are required for the accuracy for converting metric to Imperial measurements? Can one make a round-off fortune by buying tons (or tonnes) of gold in ounces and selling the same gold in kgs? Also, since the ounce is a unit of weight and not mass, can one buy gold in ounces at the equator, and then sell at the North Pole?

Each country so strongly believes that standards are extremely important, it is  imperitive that each country adopts one of its own.

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steve.taranovich
steve.taranovich
3/15/2017 4:16:13 PM
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Re: Required accuracy for PI followup
@CalcFan---thanks for these links!

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CalcFan
CalcFan
3/15/2017 12:53:56 PM
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Newbie
Required accuracy for PI followup
I just found a link related to the posting above.  The article describes pi with lots of examples and even a discussion of measuring it using a 100 foot circle.  It is from an HP Calculator newsletter.  Ooops links not allowed - yet.

Google "HP solve calculator newsletter" and look at October 2011, Issue 25, page 25.

X < > Y,

Richard

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CalcFan
CalcFan
3/15/2017 12:40:34 PM
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Newbie
Required accuracy for Pi
Another reference of the number of digits required for Pi is for the trig calculations used in HP calculatiors.  The most sensitive is the tangent function.  Since 1990 HP has used 31 digits for the internal value of Pi (truncated not rounded).

X < > Y,

Richard

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