Python is already into the movement. Let’s get into the tau revolution? `const taunumber = 6.283`

https://www.projectrhea.org/rhea/index.php/On_"Pi_is_Wrong"_and_the_Tau_Movement

Python is already into the movement. Let’s get into the tau revolution? `const taunumber = 6.283`

https://www.projectrhea.org/rhea/index.php/On_"Pi_is_Wrong"_and_the_Tau_Movement

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Yes, there is a package for tau: GitHub - JuliaMath/Tau.jl: A Julia module providing the definition of the circle constant Tau (2π)

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Indeed.

- pi
- Euler’s number
- the Euler-Mascheroni constant
- the golden ratio
- Catalan’s constant

why don’t we get tau there as well?

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It only requires to add one line of code to **mathconstants.jl**.

`Base.@irrational tau 6.28318530717958647693 tau`

I would make a pull request if I knew how to use GitHub.

There already was one, in 2013: WIP – tau: add MathConst{:τ} by StefanKarpinski · Pull Request #4864 · JuliaLang/julia · GitHub

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I am very happy to know that I was not the first one to make this request

Sorry, ignorance I suppose: but isn’t that just 2*pi?

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no, pi = tau/2

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Humor aside, the point of tau is that the fact that you have to write `2*pi`

in so many formulas shows somehow that `tau = 2*pi`

is the more fundamental number. Also, from geometry, the circumference of a circle is `tau * radius`

, and the radius is “more fundamental” because the circle is the set of points that are a given radius from the center.

Although I’m inclined to agree, I’m probably the least fanatical tau fan.

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yes, *tau* is defined by *tau = 2pi*

as dlakelan has just said, the point of *tau* is that in many important formulas in mathematics and physics, *pi* comes multiplied by 2.

There are many other formulas in math that illustrate this same point.

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Is there a unicode character for “pi with three legs”?

As everybody can see, it must be:

```
π = 2τ
```

with

```
π = 6.283185307179586
```

and

```
τ = 3.1415926535897
```

Everything else would be too confusing.

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I especially like that \tau makes radians very natural. Students often struggle with radians. My guess is, if we used \tau instead of \pi, students would find radians *more* natural than degrees. “A quarter of a circle? well that’s \tau/4 of course!”

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However, it breaks the easy relationship between radius and arclength:

L = \theta~\cdot~r

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It would be a breaking change, but I would like `2π`

to be of `Irrational`

type where the destination type changes depending on the context, rather than of `Float64`

type.

If that were the case, people who want `τ`

could just do `τ = 2π`

on their own.

I believe that is what Tau.jl does

No, a quarter of a circle is still the same number: \pi/2 = \tau/4 \approx 1.57.

It’s just silly that the standard constant (\pi) is a half-circle radians, instead of a full circle.

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Just a few minutes ago, I made an amazing mathematical discovery! We have the following:

```
julia> 411557987 / 65501488 == 2π
true
```

It seems that 2π is a simple rational number! So it should be enough to define `τ`

as follows:

```
julia> const τ = 411557987 // 65501488
```

Just kidding. How to make it:

```
julia> r = setprecision(56) do; rationalize(2big(π)) end
411557987 // 65501488
```

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Clearly, the legs of `τ`

and `π`

are *under* the fraction bar in the denominator. So one leg less makes a factor of 2 larger.

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omg, I didn’t even stop to think about it you’re totally right