add tau (τ)

[alexmo1997]

Tau is 6.283185... (2π) https://tauday.com/tau-manifesto

[foreachthing]

How about adding a custom function? I think it's easier and faster to just write 2*pi...

[alexmo1997]

Many equations are simpler when you use τ, and especially for radians, where e.g. 1/4 of a circle is 1/4τ or τ/4, it's much easier to understand and intuitive than π is. It also has a decent amount of agreement and is present in many programming languages (e.g. python, zig, nightly rust, et. al).

In addition, it does make more sense, not just for radians, but also seemingly counter-intuitively for the area of a circle with A = 1/2 * r * τ = τ/2 * r² = (tr²)/2 (this looks better with real fraction lines of course :p). Even if this may not seem as beautiful, it is there for a reason. You can come to that formular by integrating. Having the formular with pi just hides the 1/2 of the triangle 1/2 τr r`.

[hanna-kn]

There are potential conflicts with other uses of tau, which makes me hesitate. Tau currently refers to the tau lepton in libqalculate, but only for the mass of the particle and with an attached subscript.

Tau might be easier to understand and more intuitive than pi, but I highly doubt that anyone with trouble comprehending and using pi has even heard of tau.

The primary question is, does anybody actually use tau instead of pi?

How about adding a custom function?

A custom variable, with exact value 2*pi, would be more appropriate.

[alexmo1997]

There are potential conflicts with other uses of tau, which makes me hesitate. Tau currently refers to the tau lepton in libqalculate, but only for the mass of the particle and with an attached subscript.

Fair point, though I think that tau might actually be more well-known that this (might also just be my filter bubble)

Tau might be easier to understand and more intuitive than pi, but I highly doubt that anyone with trouble comprehending and using pi has even heard of tau. The primary question is, does anybody actually use tau instead of pi?

I have heared of teachers teaching the trigonometry basics with tau first which got pretty good results, it was over all easier understood than with pi. Also I do use tau pretty regulary when doing stuff, just not in libqalculate since it doesn't exist there. For me it's not just about understanding it, it's also more trivial to use.

[hanna-kn]

It is difficult for me to determine how widespread the actually use of tau, as a pi alternative, is. Google calculator recognize it, but not Wolfram alpha (as a mathematical constant tau is interpreted as the golden ratio).

I will add it to libqalculate (it will likely not do any harm), but reserve the right to remove it if alternative uses are deemed more important.

I guess there should ideally also be an option to use tau instead of pi in exact results, but I will not make it a priority.

[jerzydziewierz]

anyone that has read the tau manifesto (linked in the first post) will recognize that tau, the circle constant is a much, much better use for this high-quality symbol than any other historical uses.

quote: "(...) it is the neophytes I am most worried about, for they take the brunt of the damage (made by the adoption of pi)"

Implementing tau as the circle constant here will help to make the adoption of tau, the circle constant widespread. qalculate is great and will have lots of influence on the future.

[goyalyashpal]

Offtopic:

anyone that has read the tau manifesto that tau, the circle constant is a much, much better use for this high-quality symbol

• i haven't read the manifesto, but have seen the Vihart's video.

• and while i agree, that having the primary circle constant be C / r instead of C / d i.e. 6.28... is much more intuitive in every area of its application dealing with circles/angles

• however, i always wish that pi should had that value, with tau being half of it

• since pi rhymes with full pie, and tau looks exactly like half of pi

• (i.e. both are aesthetic reasons, but ones which are too strong to ignore for me)

this is the reason i hate tau being double of pi, and am rather sticking with status quo, even if it's bad :(

[jerzydziewierz]

• but i always wish that pi should had that value, with tau being half of it

This is not a bad idea as itself,

Just be aware that we are already fighting against 100+ years of "traditional use of the symbol pi" and hence, just introducing tau=6.28... into general use would already be a huge win,

Of course, you can always use pi=6.28... in your publications. As long as you specify what you mean by "pi", then you should be in the clear. I honestly wish you the best of luck.

In the meantime, it would be great if we had a tau symbol on the keyboard (or somewhere easy to access) in Qalculate, at all.

[goyalyashpal]

I honestly wish you the best of luck.

oh lol 🤣

[jerzydziewierz]

The primary question is, does anybody actually use tau instead of pi?

I am using it,

I am advocating for it,

I am working as a software engineer and I had actual case where using "2*PI" in the denominator of an equation caused major problems in the downstream calculations (due to omission of parentheses)

The best counter-argument for not having it is "it is not in a wide-spread use" -- and the answer is -- of course, it will not be until we begin to use it. Then, it will be used.