Linked Questions
18 questions linked to/from $\pi$ in arbitrary metric spaces
1 vote
1 answer
297 views
Does π depends on the norm? [duplicate]
If we take the definition of π in the form: π is the ratio of a circle's circumference to its diameter. There implicitly assumed that the norm is Euclidian: \begin{equation} \|\boldsymbol{x}\|_{...
3 votes
1 answer
187 views
Different "$\pi$s" [duplicate]
Does any one know of a concept analogous to $\pi$ in metric spaces. Namely, taking the all the points $1$ away from a point, and measuring the distance as some sort of limit? This was prompted when I ...
71 votes
9 answers
42k views
Why is $\pi $ equal to $3.14159...$?
Wait before you dismiss this as a crank question :) A friend of mine teaches school kids, and the book she uses states something to the following effect: If you divide the circumference of any ...
53 votes
6 answers
14k views
Why does the Hilbert curve fill the whole square?
I have never seen a formal definition of the Hilbert curve, much less a careful analysis of why it fills the whole square. The Wikipedia and Mathworld articles are typically handwavy. I suppose the ...
35 votes
2 answers
5k views
Measuring $\pi$ with alternate distance metrics (p-norm).
How/why does $\pi$ vary with different metrics in p-norms? Full question is below. Background Long ago I did an investigation on Taxicab Geometry using basic geometry. One think I recall is that a ...
19 votes
4 answers
916 views
For which $L^p$ is $\pi=3.2$?
This is a silly question that came to mind after watching numberphile video on How Pi was nearly changed to 3.2. For which $p\in(1,+\infty)$ is the ratio of the perimeter of the $L^p$ disc in $\Bbb R^...
2 votes
5 answers
628 views
The origin of $\pi$
How was $\pi$ originally found? Was it originally found using the ratio of the circumference to diameter of a circle of was it found using trigonometric functions? I am trying to find a way to find ...
2 votes
2 answers
955 views
Is the value of $\pi$ in 2d the same in 3d? [closed]
I am starting with my question with the note "Assume no math skills". Given that, all down votes are welcomed. (At the expense of better understanding of course!) Given my first question: What is ...
1 vote
0 answers
3k views
Define a circle in two dimensions in the L3 norm
So this is straight from my homework so please don't all out answer it but maybe point me in the right direction. We are learning about dimensionality and clustering algorithms and this is one ...
4 votes
1 answer
781 views
Length of a curve in normed spaces
Suppose I have a normed vectorspace $(X,\|.\|)$ and a (differential) path $\gamma:[0,1]\rightarrow X$. Can the Length of the curve be defined as $$L(\gamma)=\int_0^1\|\gamma'(t)\|\text{d}t$$ Or do ...
5 votes
6 answers
372 views
Not $\pi$ - What if I used $3$? Teaching $\pi$ discovery to K-6th grade
So, in ancient Mesopotamia they knew that they didn't really have the correct number ($\pi$) to determine attributes of a circle. They rounded to $3$. If you acted as though $\pi=3$, what shape would ...
3 votes
2 answers
403 views
Can we build a geometry in which $\pi = 42$?
More precisely, can we build a norm $N$ on $\mathbb{R}^2$, such that the ratio circumference / diameter (computed with norm $N$) of a standard circle is $42$? (By standard circle, I mean a circle ...
4 votes
1 answer
125 views
$\pi$ is dependent on properties of geometry, assuming that we define it as $C/d$. Could then the $\pi$ also be an integer?
$\pi$ is dependent on properties of geometry, assuming that we define it as $C/d$. Could there be a geometry where $\pi$ is a rational number or an integer?
8 votes
0 answers
296 views
In which $L^p$ metric is $\pi = 3.5$?
In which $L^p$ metric is $\pi = 3.5$? I am interested because it's well known that $\pi$ can range from $3.14...$ to $4$ in $L^{\infty}$
0 votes
1 answer
259 views
Is this a sensible/valid definition for "isotropic metric space"?
For a metric space, $(X,d)$, define the following: for every $x \in X$, the local similitude group, $Sim(X, x)$, is the set of all surjective similitudes $X \to X$ which fix $x$. for every $x \in X$,...