[issue12345] Add math.tau

[Danish Prakash]

Change by Danish Prakash :


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[issue12345] Add math.tau

[Simon Baird]

Change by Simon Baird :


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[issue12345] Add math.tau

[Serhiy Storchaka]

Change by Serhiy Storchaka :


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[issue12345] Add math.tau

[Pokestar Fan]

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[issue12345] Add math.tau

[Serhiy Storchaka]

Serhiy Storchaka  added the comment:

Because of its lucky number. See 
https://github.com/python/core-workflow/issues/223 (fixed).

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[issue12345] Add math.tau

[Mark Dickinson]

Mark Dickinson  added the comment:

Why does this issue keep ending up as the target of unrelated PR notifications?

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[issue12345] Add math.tau

[Serhiy Storchaka]

Change by Serhiy Storchaka :


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[issue12345] Add math.tau

[TitanSnow]

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[issue12345] Add math.tau

[Mark Dickinson]

Change by Mark Dickinson :


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[issue12345] Add math.tau

[Guido van Rossum]

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[issue12345] Add math.tau

[Christian Heimes]

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[issue12345] Add math.tau

[Mark Dickinson]

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[issue12345] Add math.tau

[Christian Heimes]

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[issue12345] Add math.tau

[Nick Coghlan]

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[issue12345] Add math.tau

[Roundup Robot]

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[issue12345] Add math.tau

[Serhiy Storchaka]

Change by Serhiy Storchaka :


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[issue12345] Add math.tau

[Chih-Hsuan Yen]

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[issue12345] Add math.tau

[TitanSnow]

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[issue12345] Add math.tau

[STINNER Victor]

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[issue12345] Add math.tau

[Roundup Robot]

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[issue12345] Add math.tau

[Guido van Rossum]

Guido van Rossum added the comment:

Thanks, fixed.

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[issue12345] Add math.tau

[Alexander Belopolsky]

Alexander Belopolsky added the comment:

There is a typo in the NEWS entry:

"Issue #12345: Add *mathemathcal* constant tau to math ..."

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[issue12345] Add math.tau

[Guido van Rossum]

Changes by Guido van Rossum :


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[issue12345] Add math.tau

[Roundup Robot]

Roundup Robot added the comment:

New changeset 68f2d6098be1 by Guido van Rossum in branch 'default':
Issue #12345: Add mathemathcal constant tau to math and cmath.
https://hg.python.org/cpython/rev/68f2d6098be1

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[issue12345] Add math.tau

[Guido van Rossum]

Guido van Rossum added the comment:

Lisa, this LGTM. I'll commit it so we can put this behind us!

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[issue12345] Add math.tau

[Lisa Roach]

Lisa Roach added the comment:

I have added some more detail to the Tau documentation, including that Tau is 2 
* pi, as well as some links to Tau Day and Vi Hart's video. 

That should give Python users enough to get started forming their own opinions 
on tau vs pi :)

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[issue12345] Add math.tau

[Chi Hsuan Yen]

Chi Hsuan Yen added the comment:

>From http://tauday.com/

> No, really, pi is wrong...

For me it's a sign that pi is (currently) more common than tau. One purpose of 
the documentation is helping newcomers understand what Python's built-in 
objects mean. "tau = 2 * pi" is better than "pi = tau / 2" as those who know pi 
only are more than those who know tau only.

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[issue12345] Add math.tau

[Emanuel Barry]

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[issue12345] Add math.tau

[Zachary Ware]

Changes by Zachary Ware :


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[issue12345] Add math.tau

[STINNER Victor]

STINNER Victor added the comment:

Chi Hsuan Yen added the comment:
> The documentation of tau should mention it's equal to 2 * pi.

According to this discussion, tau is very important. Maybe it's better to
document pi as tau/2? :-)

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[issue12345] Add math.tau

[Chi Hsuan Yen]

Chi Hsuan Yen added the comment:

The documentation of tau should mention it's equal to 2 * pi.

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[issue12345] Add math.tau

[Antoine Pitrou]

Changes by Antoine Pitrou :


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[issue12345] Add math.tau

[Antoine Pitrou]

Antoine Pitrou added the comment:

Unsubscribing from this ridiculous issue. Guido, do your thing.

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[issue12345] Add math.tau

[Stefan Krah]

Changes by Stefan Krah :


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[issue12345] Add math.tau

[Decorater]

Decorater added the comment:

not to mention I like to use the following expression myself.

pie = 22 / 7  # because why not?
tau = 2 * pie

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[issue12345] Add math.tau

[Vedran Čačić]

Vedran Čačić added the comment:

As an Easter egg, of course. I'm all for it. But please take a look at 
https://docs.python.org/3.5/search.html?q=antigravity_keywords=yes=default

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[issue12345] Add math.tau

[Georg Brandl]

Georg Brandl added the comment:

Please folks. Stop taking this so seriously and remember that this is the 
language where you can type in

>>> import antigravity

and it actually works. (Sort of.)

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[issue12345] Add math.tau

[Vedran Čačić]

Vedran Čačić added the comment:

> However an honest and non partisan web site would list all the use of pi 
> without 2 where the formula would be more complicated. I don't see that so 
> I'm still not convinced.

"non partisan" is probably hard to find, but if you want to see the other side 
of the story, http://www.thepimanifesto.com/ is probably most accessible.

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[issue12345] Add math.tau

[Xavier Combelle]

Xavier Combelle added the comment:

Python will really follow the tau sort joke ? I never saw it mentioned in any 
serious math or programming document. All the github search result looks like 
people who are in this joke (kind of).


The page http://tauday.com/state-of-the-tau list very little use of tau in 
relevant domains, the most relevant to our discussion would be the including of 
tau in modula-2 standard library.

I don't see how the introduction of the unknown tau constant in python programs 
will make them clearer or better to the targeted public who will read them.

I must confess however that 2*pi occurs frequently in formula and these formula 
would be simplified if tau was used. However an honest and non partisan web 
site would list all the use of pi without 2 where the formula would be more 
complicated. I don't see that so I'm still not convinced.

I know that Guido van Rossum is the Benevolent dictator for life of python, but 
as I understand it until this point, the dictator position was used after all 
argument took place and not before.

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[issue12345] Add math.tau

[Alexander Belopolsky]

Alexander Belopolsky added the comment:

> All that said, I agree with Mark that math.e is at best an attractive 
> nuisance.

Why don't we fix the nuisance part without making it less attractive:

class _E(float):
def __pow__(self, other):
if self is e:
return exp(other)
else:
return pow(self, other)

e = _E(2.718281828...)

> It's okay if Python occasionally shows its lighter side in unexpected places.

I would rather see

from math import π

work in the future Pythons.

I like Vi Hart, but I am firmly on the π side in the π vs. τ debate.  The 
problem with τ is that it is visually smaller than π, actually twice smaller: π 
≈ ττ, but the actual definition is the opposite.

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[issue12345] Add math.tau

[Paul Sokolovsky]

Paul Sokolovsky added the comment:

What about rounding pi to 3 (and tau to 6)?

https://en.wikipedia.org/wiki/Indiana_Pi_Bill (and I'm sure we can find a cute 
video about how cool to have pi as 3 to add it to the docs).

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[issue12345] Add math.tau

[Tim Peters]

Tim Peters added the comment:

Serhiy's objection is a little subtler than that.  The Python expression 
`math.log(math.e)` in fact yields exactly 1.0, so IF it were the case that x**y 
were implemented as

math.exp(math.log(x) * y)

THEN math.e**500 would be computed as math.exp(math.log(math.e) * 500) == 
math.exp(1.0 * 500) == math.exp(500.0).

But that's not how x**y is implemented.  Because the error in log() is 
multiplied by y, and then fed into exp() blowing it up even more, only a 
hopelessly naive library would implement pow() that way.  In practice, library 
pow functions fake the effect of at least 15 more bits than native double 
precision to absorb these errors.

Under the covers, then, a reasonable library pow computes math.log(math.e) to 
more than native double precision - and _that_ (internal, invisible) result is 
not 1.0.  Because math.e isn't the mathematical e to begin with.  The 
difference between math.e and the mathematical e is a difference quite visible 
to the internal log, which delivers an internal log not equal to 1, and its 
difference from 1 is "an error" multiplied by 500 and fed into the internal exp 
(blowing up the error even more).

In the end, math.e**500 returns a very good approximation to the true value, 
_given_ that math.e is not e.  There's no reason to hope that's close to 
exp(500), though - that delivers a very good approximation to e**500 (where `e` 
is the true e).  The larger the exponent, the more different math.e**y _should 
be_ from exp(y), and for the same fundamental reason 2**y differs from 3**y (or 
plug in any other pair of distinct bases).

All that said, I agree with Mark that math.e is at best an attractive nuisance. 
 Still, I'm -1 on removing it - it's a traditional and universally embraced 
nuisance ;-)

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[issue12345] Add math.tau

[STINNER Victor]

STINNER Victor added the comment:

> math.e**500 = math.exp(math.log(math.e)*500)

That's the theory if numbers have an infinite precision. In practice,
intermediate results are rounded and have a limited precision.

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[issue12345] Add math.tau

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

> To give just one example, on my machine, the result of `exp(500)` has an
> error of 0.42 ulps, while `math.e**500` gives an error of over 150 ulps.

How can it be? math.e**500 = math.exp(math.log(math.e)*500) and 
math.log(math.e) is 1.0.

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[issue12345] Add math.tau

[Mark Dickinson]

Mark Dickinson added the comment:

BTW, if we're talking about useless constants in the math module, it's hard to 
get more useless than `math.e`: it's rare for `e` to turn up in formulas except 
in the form `e**`, and the latter case is better catered for by the 
more accurate (and usually faster) expression `exp(`. I'd even go so 
far as to call `math.e` *worse* than useless, since its presence leads people 
astray by encouraging them to write `math.e**x` instead of `exp(x)`.

To give just one example, on my machine, the result of `exp(500)` has an error 
of 0.42 ulps, while `math.e**500` gives an error of over 150 ulps.

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[issue12345] Add math.tau

[Mark Dickinson]

Mark Dickinson added the comment:

The unification of tau2.diff and tau3.diff LGTM; thanks, Lisa!

My commit bit is broken at the moment; anyone in a position to apply those 
patches?

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[issue12345] Add math.tau

[Lisa Roach]

Lisa Roach added the comment:

I've updated the test to assert tau is equal to 2*math.pi, as well as updated 
the docs and cmath.

Let me know if I have made any errors!

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Added file: http://bugs.python.org/file44080/tau3.diff

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[issue12345] Add math.tau

[Guido van Rossum]

Guido van Rossum added the comment:

FWIW I don't plan to have more constants there, at the current rate we'll
be fine for centuries. :-)

What worries me more is proposals to add Python functions to math...

--Guido (mobile)

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[issue12345] Add math.tau

[Aaron Meurer]

Aaron Meurer added the comment:

Emanuel Barry, that is both untrue and irrelevant (sorry to be blunt, but 
that's a total straw man on my and I believe other's argument). The fact that 
the only mathematical constants in math are pi and e (nan and inf aren't really 
"mathematical" constants) *does* indicate to me that only the really important 
ones are included. 

GvR, are you also in favor of adding more math constants/functions to the math 
module? I do see the value of Easter eggs in the language, but two real 
constants and one Easter egg constant seems weirder than ten real constants and 
one Easter egg constant. I'm +1/(2*pi) (because I still think tau in general is 
stupid) to add it if it also means the math module can be expanded. And before 
you ask, yes, I'll be happy to contribute once things move to GitHub.

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[issue12345] Add math.tau

[Guido van Rossum]

Guido van Rossum added the comment:

Let those other libraries follow.

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[issue12345] Add math.tau

[Emanuel Barry]

Emanuel Barry added the comment:

I think that whether or not something is trivial doesn't really correlate to 
whether or not it has its place in the language. After all, `math.pi` is 
3.1416, and most people using pi will not worry about more than 4 decimal 
digits. Those who do are presumably using something better than floating-point 
arithmetic to begin with ;)

For yet another colour to paint this tiny bikeshed, maybe we could put new 
constants in something like `math.constants`, with aliases to existing ones. Of 
course, I don't mean to point out how ridiculously disproportioned this 
discussion is, but...

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[issue12345] Add math.tau

[Stefan Krah]

Stefan Krah added the comment:

Aaron, I may be wrong, but I understood this to be something like:

>>> from __future__ import barry_as_FLUFL
>>> 3 <> 10
True


I *do* hope sympy supports that! :-)

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[issue12345] Add math.tau

[Aaron Meurer]

Aaron Meurer added the comment:

I also wonder, if math will be gaining constants that no one uses like tau, if 
it will also gain constants that people actually do use (currently math just 
has pi, e, inf, and nan). [i for i in dir(numpy) if isinstance(getattr(numpy, 
i), float)] reveals euler_gamma as one example. 
https://docs.scipy.org/doc/scipy/reference/constants.html lists a bunch more. 

And if we're adding derived constants, why not loge2, another derived 
constants, used way more often than tau?

In case you can't tell, I'm opposed to adding tau, although fwiw I do think it 
would be nice to add some of the other constants I mentioned above like 
euler_gamma to math, and in general, I support adding more stuff to math (but 
only generally useful stuff, obviously; there's no need to port all of 
scipy.special, for instance).

As an aside, a technical note on the patch: for consistency, it should also be 
added to the cmath library (pardon me if I misread the patch and that's already 
happening).

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[issue12345] Add math.tau

[Aaron Meurer]

Aaron Meurer added the comment:

If this is implemented, it would be (as far as I can tell) the only thing in 
the math module that isn't also implemented in any of the standard external 
math libraries. None of numpy, scipy, sympy, or mpmath implement tau (if I'm 
missing one that others think is equally important to the ecosystem, let me 
know).

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[issue12345] Add math.tau

[Antoine Pitrou]

Antoine Pitrou added the comment:

The patch needs a documentation update, by the way.

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[issue12345] Add math.tau

[Aaron Meurer]

Changes by Aaron Meurer :


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[issue12345] Add math.tau

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

In general, the volume, in n-dimensional Euclidean space, of the unit n-ball, 
is given by

V_n = pi**(n/2) / gamma(n/2+1)

or

V_n = (tau/2)**(n/2) / gamma(n/2+1)

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[issue12345] Add math.tau

[Antoine Pitrou]

Antoine Pitrou added the comment:

Le 11/08/2016 20:07, Tim Peters a écrit :
> 
> For those insisting that tau is somehow unnatural, just consider
> that the volume of a sphere with radius r is 2*tau/3*r**3 - the formula using
> pi instead is just plain impossible to remember ;-)

Thank you, I'm totally convinced now :-)

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[issue12345] Add math.tau

[Evelyn Mitchell]

Changes by Evelyn Mitchell :


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[issue12345] Add math.tau

[Tim Peters]

Tim Peters added the comment:

For those insisting that tau is somehow unnatural, just consider that the 
volume of a sphere with radius r is 2*tau/3*r**3 - the formula using pi instead 
is just plain impossible to remember ;-)

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[issue12345] Add math.tau

[Vedran Čačić]

Vedran Čačić added the comment:

Guido once again shows he is not a mathematicians (honestly, most of the 
"arguments" for tau are plain nonsense), but he is a fantastic popularizer. I 
(and most of the other professional mathematicians) will love Python a tiny bit 
less, but a horde of people will love it more, and it's a fine tradeoff. :-)

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[issue12345] Add math.tau

[Guido van Rossum]

Guido van Rossum added the comment:

It's okay if Python occasionally shows its lighter side in unexpected places. 
Think of the delight of future (junior) high schoolers who discover that Python 
participates in the tau debate. :-)

Also, I think this video by Vi Hart should be linked to from the docs for this 
constant: https://www.youtube.com/watch?v=jG7vhMMXagQ

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[issue12345] Add math.tau

[Nofar Schnider]

Nofar Schnider added the comment:

I agree with Raymond.
In my opinion, it doesn't seem like there is a need to add such a constant.
I know many of my previous and current colleagues would not use it (why should 
them if they can just write "2 * math.pi" ?)
It seems that the efforts to spread the word that Pi is wrong and Tau is right 
haven't "bear fruits". For now I don't think we should make such a strong stand 
in adding it.
If we do add new constants they should be of calculations that are harder and 
might ruin the code's visibility.
 
https://www.explainxkcd.com/wiki/images/0/08/pi_vs_tau.png

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[issue12345] Add math.tau

[Evelyn Mitchell]

Evelyn Mitchell added the comment:

I also agree with Raymond's arguments. Adding tau doesn't add clarity to the 
math module, it just adds complexity.

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[issue12345] Add math.tau

[Antoine Pitrou]

Antoine Pitrou added the comment:

Agreed with Raymond's arguments.

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[issue12345] Add math.tau

[Guido van Rossum]

Guido van Rossum added the comment:

Noted, but it doesn't change my decision. Obscure fact: did you know there
are also branches of mathematics and engineering that define pi to for
something else?

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[issue12345] Add math.tau

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

+1 to Raymond.

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[issue12345] Add math.tau

[Raymond Hettinger]

Raymond Hettinger added the comment:

Perhaps minds are already made up, but this may be the last chance to say that 
I think that this shouldn't go forward.

* The push to use of "tau" has the flavor a political fad or wishful thinking 
that may or may not succeed.  The math module should only implement established 
practice.

* Since not everyone knows or uses tau, its use would tend to make code less 
clear. As a reviewer, I would ask that code like "from math import tau" to be 
changed to "from math import tau as twopi".  The latter is more clear to most 
users (how many people would recognize "tau * r" when it occurs in the middle 
of a larger expression?).  

* I've surveyed engineers in my recent Python courses (often with Physics, EE, 
MaterialScience, DSP, or CompSci backgrounds and not a single one of them had 
heard of this constant).

* If people really wanted this, we would be seeing more cases of "tau = 2.0 * 
math.pi" in code.  Google searches and Github code search shows that this is 
very rare.

* It is already trivial to write "tau=2.0*pi" so why bother?

* Adding mysteriously named constants degrades the usability of the math module 
where many of the tools are currently self-evident but not all (
tau is a number, gamma is a function, and what the heck is a frexp?).

* Also, the name "tau" is already used for other purposes in various contexts 
(shear stress, proper time in relativity, torque, tau lepton, optical depth in 
astronomy, time contacts in RC circuits, etc).

If needed, I can survey the audiences at the upcoming SF PyData conference and 
the SF PyBay conference to see if any of the participants have any clue what 
this is about and whether they would support the addition.

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[issue12345] Add math.tau

[Mark Dickinson]

Mark Dickinson added the comment:

At some point before 3.6, the docs should get updated, and `cmath` should get 
the `tau` constant too.

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[issue12345] Add math.tau

[Mark Dickinson]

Mark Dickinson added the comment:

> I'd test that tau is exactly equal to 2*pi.

+1

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[issue12345] Add math.tau

[Tim Peters]

Tim Peters added the comment:

Hmm.  I'd test that tau is exactly equal to 2*pi.  All Python platforms  (past, 
present, and plausible future ones) have binary C doubles, so the only 
difference between pi and 2*pi _should_ be in the exponent (multiplication by 2 
is exact).  Else we screwed up one or both mantissas (typed the constant wrong, 
and/or the C compiler is rounding incorrectly) - which would be bad.

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[issue12345] Add math.tau

[Guido van Rossum]

Guido van Rossum added the comment:

OK, here's a diff with a test that math.tau ~~ 2*math.pi.

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[issue12345] Add math.tau

[Zachary Ware]

Zachary Ware added the comment:

Builds fine on Windows.  Happily, `math.tau == 2*math.pi` is True.

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stage: needs patch -> commit review
versions: +Python 3.6

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[issue12345] Add math.tau

[Guido van Rossum]

Changes by Guido van Rossum :


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Added file: http://bugs.python.org/file44063/tau.diff

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[issue12345] Add math.tau

[Guido van Rossum]

Guido van Rossum added the comment:

I'm just going to do this.

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[issue12345] Add math.tau

[Roundup Robot]

Roundup Robot added the comment:

New changeset 761b370f2cfd by Terry Jan Reedy in branch '3.3':
#12345: null merge with 3.2.
http://hg.python.org/cpython/rev/761b370f2cfd

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[issue12345] Add math.tau

[Terry J. Reedy]

Changes by Terry J. Reedy tjre...@udel.edu:


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Removed message: http://bugs.python.org/msg184297

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[issue12345] Add math.tau

[Waldir Pimenta]

Waldir Pimenta added the comment:

Following-up sbaird's comment, I must point out that those aren't 
Python-specific results. Filtering them by appending l=python to the urls 
yields:
- TAU = 2 * Math.PI: 6
- TAU = 2*Math.PI: 2
- TAU=2*Math.PI: 0
- TAU = Math.PI * 2: 0
- TAU = Math.PI*2: 2
- TAU=Math.PI*2: 1
(total: 11)

- TAU = 2 * PI: 9
- TAU = 2*PI: 12
- TAU=2*PI: 0
- TAU = PI * 2: 2
- TAU = PI*2: 0
- TAU=PI*2: 0
(total: 23)

Then again, the results for all languages are still helpful to estimate the 
overall adoption of the notation in code, and indeed the global usage of these 
patterns (in github only) is in the hundreds.

Also, it's worth taking a look at the usage of the twopi constant, which is 
already defined in several languages 
(http://en.wikipedia.org/w/index.php?oldid=509096802#Support_in_programming_languages),
 and has been manually defined in python quite often, proving its usefulness:

- https://github.com/search?l=pythonq=twopitype=Code (~2k results in python, 
and ~58k overall)
- https://github.com/search?l=pythonq=two_pitype=Code (~200 results in 
python, ~23k overall)

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[issue12345] Add math.tau

[Simon Baird]

Simon Baird added the comment:

https://github.com/search?q=%22TAU+%3D+2+%2A+Math.PI%22type=Code
https://github.com/search?q=%22TAU+%3D+PI+*+2%22type=Code

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[issue12345] Add math.tau

[Éric Araujo]

Changes by Éric Araujo mer...@netwok.org:


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[issue12345] Add math.tau

[Éric Araujo]

Changes by Éric Araujo mer...@netwok.org:


Removed file: http://bugs.python.org/file22397/unnamed

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[issue12345] Add math.tau

[Guido van Rossum]

Guido van Rossum gu...@python.org added the comment:

Uh, not until I've seen a lot more evidence that people are habitually writing 
TAU = 2 * math.pi in their programs...

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[issue12345] Add math.tau

[Daniel Stutzbach]

Daniel Stutzbach stutzb...@google.com added the comment:

On Wed, Jun 15, 2011 at 8:10 PM, Nick Coghlan rep...@bugs.python.orgwrote:

 I'd like to add a new constant to the math module:

  tau = 2*math.pi

 Rather than repeating all the reasons for why tau makes more sense than pi
 as the fundamental circle constant, I'll just refer interested readers to
 http://tauday.com/

(The following is best if read aloud using your best pirate impression)

I'd rather name the new constant matey.  Then we have:

The circumference of a circle is: r matey
The area of a circle is: one-quarter r r matey
etc.

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Added file: http://bugs.python.org/file22397/unnamed

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___div class=gmail_quoteOn Wed, Jun 15, 2011 at 8:10 PM, Nick Coghlan span 
dir=ltrlt;a 
href=mailto:rep...@bugs.python.org;rep...@bugs.python.org/agt;/span 
wrote:brblockquote class=gmail_quote style=margin:0 0 0 
.8ex;border-left:1px #ccc solid;padding-left:1ex;
I#39;d like to add a new constant to the math module:br
br
  tau = 2*math.pibr
br
Rather than repeating all the reasons for why tau makes more sense than pi as 
the fundamental circle constant, I#39;ll just refer interested readers to a 
href=http://tauday.com/; target=_blankhttp://tauday.com//a/blockquote
divbr/divdiv(The following is best if read aloud using your best pirate 
impression)/divdivbr/divdivI#39;d rather name the new constant 
quot;mateyquot;.  Then we have:/divdivbr/divdivThe 
circumference of a circle is: r matey/div
divThe area of a circle is: one-quarter r r 
matey/divdivetc./div/divbr-- brDaniel Stutzbachbr
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[issue12345] Add math.tau

[Mark Dickinson]

Mark Dickinson dicki...@gmail.com added the comment:

Not to mention d(area of circle of radius r) = r dr matey.

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[issue12345] Add math.tau

[Georg Brandl]

Georg Brandl ge...@python.org added the comment:

 http://tauday.com/

And I thought putting dx directly next to the integral sign was audacious...

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[issue12345] Add math.tau

[Raymond Hettinger]

Raymond Hettinger raymond.hettin...@gmail.com added the comment:

-1

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[issue12345] Add math.tau

[Nick Coghlan]

Nick Coghlan ncogh...@gmail.com added the comment:

The golden ratio is more commonly denoted with phi (although tau does get used 
sometimes).

Popularity isn't the point though, it's the fact that tau *makes geometric 
sense* in ways that 2*pi doesn't.

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[issue12345] Add math.tau

[STINNER Victor]

STINNER Victor victor.stin...@haypocalc.com added the comment:

I like this issue number, but I don't think that Python needs this new 
constant: it's trivial to add it to your own project. We have pi and e, it's 
enough. If we begin to add a new constant, others will ask to add much more 
constants, and there are million of other constants (useful or not). You may 
want to create a library of some other common constants. You can use 
float.fromhex() to have a good accuracy.

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[issue12345] Add math.tau

[Antoine Pitrou]

Antoine Pitrou pit...@free.fr added the comment:

Nick, you just have to write: tau = 2 * math.pi
and you're done.

 there are million of other constants

Actually, I've heard there are an infinity of them.

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[issue12345] Add math.tau

[STINNER Victor]

STINNER Victor victor.stin...@haypocalc.com added the comment:

 Actually, I've heard there are an infinity of them.

Can you prove that?

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[issue12345] Add math.tau

[Antoine Pitrou]

Changes by Antoine Pitrou pit...@free.fr:


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[issue12345] Add math.tau

[Benjamin Peterson]

Benjamin Peterson benja...@python.org added the comment:

2011/6/16 STINNER Victor rep...@bugs.python.org:

 STINNER Victor victor.stin...@haypocalc.com added the comment:

 Actually, I've heard there are an infinity of them.

 Can you prove that?

Don't have to. Axiom of infinity. :)

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[issue12345] Add math.tau

[Simon Baird]

Changes by Simon Baird simon.ba...@gmail.com:


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[issue12345] Add math.tau

[Nick Coghlan]

New submission from Nick Coghlan ncogh...@gmail.com:

I'd like to add a new constant to the math module:

  tau = 2*math.pi

Rather than repeating all the reasons for why tau makes more sense than pi as 
the fundamental circle constant, I'll just refer interested readers to 
http://tauday.com/

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nosy: ncoghlan
priority: normal
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stage: needs patch
status: open
title: Add math.tau
type: feature request

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[issue12345] Add math.tau

[Benjamin Peterson]

Benjamin Peterson benja...@python.org added the comment:

Perhaps we should wait until \tau gains popularity larger than some impassioned 
physicist. \tau has been used to represent the golden ratio longer.

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