Date: Sat, 5 Mar 2022 20:19:12 -0500

On Sat, Mar 5, 2022 at 9:48 AM Desmond Gold Bongcawel via Std-Proposals <

std-proposals_at_[hidden]> wrote:

> [resent the mail]

>

> I know this is a silly minor addition, but this would help reduce the

> duplication of writing (std::numbers::pi * 2) wherever they exist in some

> particular computations such as computing the circumference of the circle.

>

> The constant tau already existed in other programming languages such as

> C#, rust, etc.

>

https://doc.rust-lang.org/stable/std/f64/consts/constant.TAU.html

https://docs.microsoft.com/en-us/dotnet/api/system.math.tau

https://stackoverflow.com/questions/13426562/why-does-math-h-define-pi-pi-2-2-pi-but-not-2pi

I'm familiar with https://tauday.com/tau-manifesto , but still, you're

going to have an uphill battle explaining why "tau_v" would be a better

name than "twopi_v". The only obvious benefit of naming it "tau" would be

that 100 years from now, when everyone's using tau for all their

mathematical needs, C++ won't be ridiculed for having outdated nomenclature

that feels like it's stuck in the (400s BC through 2000s). ;)

expression equivalent to:

> 2 * std::numbers::pi_v<T>

>

(For dummies like me who might also be fooled by this at first: No, this is

not "shifting in a zero from the right" and thus losing one bit of

precision in the mantissa. It's just taking M_PI and increasing the

exponent by 1. So this is indeed mathematically correct.)

â€“Arthur

std-proposals_at_[hidden]> wrote:

> [resent the mail]

>

> I know this is a silly minor addition, but this would help reduce the

> duplication of writing (std::numbers::pi * 2) wherever they exist in some

> particular computations such as computing the circumference of the circle.

>

> The constant tau already existed in other programming languages such as

> C#, rust, etc.

>

https://doc.rust-lang.org/stable/std/f64/consts/constant.TAU.html

https://docs.microsoft.com/en-us/dotnet/api/system.math.tau

https://stackoverflow.com/questions/13426562/why-does-math-h-define-pi-pi-2-2-pi-but-not-2pi

I'm familiar with https://tauday.com/tau-manifesto , but still, you're

going to have an uphill battle explaining why "tau_v" would be a better

name than "twopi_v". The only obvious benefit of naming it "tau" would be

that 100 years from now, when everyone's using tau for all their

mathematical needs, C++ won't be ridiculed for having outdated nomenclature

that feels like it's stuck in the (400s BC through 2000s). ;)

expression equivalent to:

> 2 * std::numbers::pi_v<T>

>

(For dummies like me who might also be fooled by this at first: No, this is

not "shifting in a zero from the right" and thus losing one bit of

precision in the mantissa. It's just taking M_PI and increasing the

exponent by 1. So this is indeed mathematically correct.)

â€“Arthur

Received on 2022-03-06 01:19:25