PhiPhenomenon wrote:

(#11)
There's a pretty cool infinite sum that can be used to calculate pi:

(I swear there's an image, cubeupload's just down)
However, it's pretty slow. You have to sum like the first thousand terms of the terms to get like the first four places of pi.

There's a faster one called the Machin formula, but it requires a little more math:

(There's also an image here)
You can find the arctangent block from the operators section:

([atan v] of ())

Scratch is not precise enough.

* * *

Decimals in Scratch aren't infinitely precise. The computer uses 58 bits, which equates to about 10 digits.

mumu245 wrote:

PhiPhenomenon wrote:

(#11)
There's a pretty cool infinite sum that can be used to calculate pi:

(I swear there's an image, cubeupload's just down)
However, it's pretty slow. You have to sum like the first thousand terms of the terms to get like the first four places of pi.

There's a faster one called the Machin formula, but it requires a little more math:

(There's also an image here)
You can find the arctangent block from the operators section:

([atan v] of ())

Scratch is not precise enough.

* * *

Decimals in Scratch aren't infinitely precise. The computer uses 58 bits, which equates to about 10 digits.

If the OP wanted to, they could use the arbitrary-precision arithmetic described in Super Pi Calc by DadOfMrLog. To avoid loss of precision from Scratch decimals, it uses lists to keep track of individual terms. Then it manually sums them together instead of using the addition operator.

I have a project that does this: https://scratch.mit.edu/projects/982730462/

Edit: I recommend using method 3 (The Gregory-Leibniz series), because while it doesn't converge quite as quickly as method 2 (the Nilakantha series), scratch “lets” it be more accurate once it's finished

This is the most accurate way to calculate pi:

1/π = 12 * ∑ ((-1)^k * (6k)! * (13591409 + 545140134k) * (3k)! * (k!)^3) / (640320^(3k+3/2))

Unfortunately, there's no sum operator ( ∑ ) in scratch so… yeah. The Chudnovsky Algorithm doesn't work well on scratch.

TutoeTurtle wrote:

This is the most accurate way to calculate pi:

1/π = 12 * ∑ ((-1)^k * (6k)! * (13591409 + 545140134k) * (3k)! * (k!)^3) / (640320^(3k+3/2))

Unfortunately, there's no sum operator ( ∑ ) in scratch so… yeah. The Chudnovsky Algorithm doesn't work well on scratch.

I made a program with that algorithm. The problem is I didn't plan for having more than 16 digit precision, so it doesn't get that many digits. It's fast though! https://scratch.mit.edu/projects/1145688427/

TheUltimateHoodie wrote:

PhiPhenomenon wrote:

TheUltimateHoodie wrote:

but my teacher said to use that

did my teacher lie to me?

The OP wants an approximation of pi that goes on as long as they can. 22/7 comes out to about 3.1428. That's a 0.0403% error from the actual value of pi, so it's fine to use in calculations. However, it's 3rd decimal place is already wrong.

so…my teacher lied…she said 22/7 WAS pi

Yup she either didn't know or was just simplifying so you could remember it better.

TheUltimateHoodie wrote:

Vaibhs11 wrote:

london11gm wrote:

22/7 = pi

That is a terrible estimation of pi compared to what OP's asking for.

but my teacher said to use that

did my teacher lie to me?

its just for easier calculation, as pi is irrational

there are actually a lot of ways to find pi

Shrek_em wrote:

circumference / diameter

It's impossible to do this, because we cannot measure the circumference and diameter of a circle perfectly. It is a good estimation, but not good enough.

MrKingofScratch wrote:

here's a funny approach
https://scratch.mit.edu/projects/682780554/

WHY DOES IT SAY Last edited by kaj (Tomorrow 00:00:00)

-20thaccount- wrote:

MrKingofScratch wrote:

here's a funny approach
https://scratch.mit.edu/projects/682780554/

WHY DOES IT SAY Last edited by kaj (Tomorrow 00:00:00)

It is just a part of his signature. In case you didn't know, kaj is an older user that made a big commotion about hacking scratch to get attention.

last edited by skibidifarm (-100 BC 99:99:99)