## 5735 Reputation

15 years, 75 days

## Pi week +1...

I never realized Albert Einstein's birthday was on Pi day, that's pretty neat.

I have heard some carpenters use the 22/7 approximation which is accurate to 2 decimal places and usually more than accurate enough for their needs.  I found it amazing that Babylonians approximated Pi as 3 and the Egyptians using Pi approximation as 3.14.  Of course at the time they diddn't know more.

A lesser known approximation with even better accuracy is the fraction 355/113 accurate to 6 decimal places.  Although, remembering that or simply remembering 3.141592 seems to be just as easy.  However 3.14159265 rolls off the tongue just as easy and is even easier to remember.

Apparently NASA uses Pi to 15 decimal places.  At least that was a common answer they gave to questioning individuals.  During number crunching using computers I find it hard to believe they would truncate Pi at 15 decimal places.

I started looking around to see if there was an algorithm that would find digits of Pi without having to carry all the previous digit calculations.  Turns out an algorithm exists but only in hexadecimal, known as the BBP formula discovered in 1995 by David Bailey, Peter Borwein and Simon Plouffe (can't paste formula in at the moment).  Unfortunately there's no analogy in decimal form, but it is argued that the amount of power required to determine those digits require just as much energy in calculating normally.

## Deleted post checks...

There's probably a few ways these deleted posts could be handled.  I agree that if a post contains legitamate content or contributable content it should not be deleted.  Or if at least 3 moderators have agreed to have it deleted as long as there are no counter votes, with a debatable reason, for having it deleted.

A tag could be applied to a post/question stating that "User A" has requested content be deleted with reason, say for example "this is a duplicate" etc..

## Shortly...

So sometime from now and in the next couple of weeks.

## @opus64 Prebens 3rd solution is the way ...

@opus64 Prebens 3rd solution is the way to go, select a single term to isolate and just add the others.

## system(cls);...

@Phuocminh94 system(cls); will clear the screen.

**edit add** followed by using the restart; command to reset everything.  In older maple versions gc(); was for garbage collection and cleared out the memory - maple became more efficient in doing so in more recent versions so gc() become mostly unnecessary.

## sin(x)...

@Phuocminh94 Try using sin(x) instead of just sin

## Error...

I get an error as well

p1:=plot(sin):
display[plots](p1);

Error, no plot device driver for plotdevice=colorchar

edit**** It appears colorchar doesn't appear in the help so it is not supported in 2018.

## Thanks...

@acer Thanks.  Indeed they are!

## Good enough...

@vv Good enough then, nuff said, case closed.

## autosave...

This is concerning.  I wonder if it depends on which one is opened first and if autosave is on.  Was your autosave on?

## CRTL + m and CRTL + r...

CRTL + m : changes maple input

CRTL + r : 2D math mode

## expectations...

What kind of fit line are you expecting?  Since you don't think it fits well, it's not what you are expecting.  If you could draw a rough line of what you expect it to be maybe we could find one that fits better.

## approximation only...

@jud Some functions have no simple anti-derivatives, and in cases where a definite integral is needed it will have to be approximated.

In your case Maple and Mathematica can only produce an approximate numerical result.  No exact variable solution at this time exists.

## different...

Since all maple versions are providing the same answer, I suspect your equation is slightly different from last year or some kind of strange variable substitution.

Over time the mind does play tricks you know, and if you hadn't exactly saved the worksheet then we grasp at straws.

## more points...

@permanoon123  For me, there aren't enough points to extrapolate to any kind of reasonable curved surface or 3d structure.  Do you have more points?  What is it supposed to be?  From the points you show I don't see how it could have produced that image you provide from surfer software.

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