Survey posted 2002-03-16 13:51 by Henrik.

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yeah, I celebrated that day... it wuz the one year anniversary for my girlfriend and me, so I guess I would have to say I celebrated that day, if not by accident...

PI day. Well I didn't know of it. March 14th hmmm. 03/14. Or this year 020314. Anyway.

3.14... if you take the decmial digits 14.. to 144 places and sum the digits. You get 666. Really.

Now if you have a program that can carry out a arithmetic to a specific number of places the following algorithm will quickly generate the value of PI to that many places, assuming the accuracy is also to that many places:

Do loop
Let E = A
Let B = 2 x B
Let A = (A + C) / 2
Let C = sqrt(C x E)
Let D = D - [B x (A - E)^2]
Then PI = (A / 2)^2 / (4 x D)
Loop

The above is written in a pseudo code. And is found on page 69 (less "Do Loop") in "Barron's Mathematics Sudy Dictionary." The inside front and back cover has PI to 500 decimal places.

Now a square root algorithm:

new value = 1
do loop
old value = new value
new value = (number + old value^2) / (2 x old value)
loop

And when, before making the old value equal to the new value, the new value no longer changes from the last old value: You have then arrived at the square root of the number to the accuracy or precision of the calculation. This algorithm can found a number of places. My source is "Calculator Calculus" by George McCarty.

well, just download the picalc program from the archives. very accurate. and rather good speed. on hw1 ti-89 took only 47 minutes to calculate 10000 decimal places. and it can store to text files. (the first accurate calculation to 10k places took 2.2 hours! hehe)

Well if you had a calculator program that could do 10,000 place calculations that algorithm I refered to would be much much faster.

Here is an idea, write a simple programmable calculator program for up to 30,000 place calculations. Addition, subtraction, multiplication, division. A minimum of 420K for storage of variables. The program less work space would have to be under 80K. Part of the 420K would have to be 120K work space.

Your squareroot algorithm is called the Newton-Raphson for finding the roots of a differentiable function. In more general terms the algorithm can be written like this:
x(n+1) = f(x(n))/f'(x(n)), where f(x(0)) = 0
You just keep doing this calculation until you get a decent result. This way you can use the algorithm for any differentiable function.

I actually think it's the way the solve function works in many TI calculators (probably a bit enhanced though).

Cuco

Honestly..no.

All I know about Pi is that it's 3.14 and if you square it, it equals 10.

no it doesn't! pi^2=9.869044...

Yep, I was thinking the same thing. PI^2 = 9.86960. . . rounded off to two places like 3.14 is 9.87 . . . .

Rounded off for 3.1 value of PI is 9.9

Round PI off to 3 then PI squared is 10 not 9. But 3 squared is 9.

So if you take PI in our calculator and set FIX mode to 0. PI would be 3 and PI^2 would be 10.

PI at fix 2, PI is 3.14 and PI^2 is 9.87 not 10.

>Round PI off to 3 then PI squared is 10 not 9. But 3 squared is 9.

What? that made absolutely NO sense.

anyways, in 5th grade I spent a month trying to calculate the square root of 10 b/c I wanted more than 8 digits but the only calcs I knew of were those little stupid ones.
(sqrt)10=3.16227 76601 68379 33199 88935 44432 72....

NOT 3.14159 26535 89793 28462 43383 2795...(pi)

I did something similar. In 7th grade, I was bored and wanted to prove that 5/7 was an repeating decimal...At the end of my little quest I had about 70 sheets of paper that calculated out, via long division, the first thousand or so digits...And the same pattern showed up again and again. Boy, I was stupid.

Haven't you noticed that with long division if ever one part of the sequence starts to repeat the whole number must be recurring as this is like a loop in a program - if this occurs go to loop - it always occurs.

Of course I know that. I knew that then. I was bored.

oh yeah, I fooled around with fractions and repeating decimals a lot when I was in 5th grade. Hm... I wonder if there is a Javascript day?

PI in fix 0 mode is 3. PI^2 in fix 0 mode is 10

PI in fix 1 mode is 3.1
PI^2 in fix 1 mode is 9.9

PI in fix 2 mode is 3.14
PI^2 in fix 2 mode is 9.87

>>Round PI off to 3 then PI squared is 10 not 9. But 3 squared is 9.

>What? that made absolutely NO sense.

Really?

PI in fix 0 mode is 3. PI^2 in fix 0 mode is 10

that's because it doesn't round PI to 3.
it finds PI^2 and rounds that (about 9.87)
to the nearest ones place.

ex: FIX 0
3.4+3.4=7
not 6 because it finds the solution (6.8)
and rounds that

(to do it right:)
round(PI,0)^2
(at least so on the TI-89 because of the round() function)

you see,
fix 0 mode only rounds the final answer
and leaves PI as 3.14159... when you square it

so,
round PI to 3 and then PI^2=9

you see,
fix 0 mode only rounds the final answer
and leaves PI as 3.14159... when you square it

so,
round PI to 3 and then PI^2=9

sorry for any confusion

An interesting fact on the numbers...

Pi Day = 3-14

In order to be accurate, the last most accurate Pi Day would have been Mar 14, 1592 or 3-14-1592.

Likewise: 3-14 159 AD
Mar 14 15 AD
and Mar 14 1 AD.

The next "accurate" Pi day would be Mar 14, 15926.

Or, within 20 years, 3-14-15. (Mar 14 2015)

Okay, my presense was felt. If I confused anyone, I'm sorry.

~Chuck

I think to accomodate more digits of pi, it is celebrated at 1:59 pm. That's 3-14 1:59p. :-)

and 26 seconds

Or, Mar 14 2015 @ 9:26:53 am

3-14-15 9:26:53