Tagged Questions
2
votes
1answer
69 views
probability involving matching of discrete shapes on a square grid
Figure F exists on a regular square grid.
T transforms F by any combination of horizontal or vertical reflection as well as rotation by 90 or 180 degrees.
A larger background grid of X by Y contains ...
2
votes
3answers
267 views
How to calculate the area of bizarre shapes
I'm looking for an algorithm to calculate the area of various shapes (created out of basic shapes such as circles, rectangles, etc...). There are various possibilities such as the area of 2 circles, 1 ...
2
votes
4answers
296 views
What is the correct value of $\pi$
I have seen that:
$\pi = 22/7$
$\pi = 3.14\ldots$
$\pi = 17 - \sqrt{192}$.
$22/7 \gt \pi$
$22/7 \lt\pi$
My brain storming doubt was, is A = B? Is B = C? Is C= A = B? how D and E are correct or ...
0
votes
1answer
98 views
calculate surface normal with random sampling of points
Given a surface in $R^3$ and a point P on the surface, I want to calculate the surface normal in this point, the vector that is perpendicular to the surface.
However, I do not know the whole surface, ...
0
votes
0answers
97 views
How do I create a shape from a square corners' values?
I'm working on a 3D algorithm, so my problem applies to cubes, not squares. But for convenience, I'll stick to 2D.
Each corner of a square can contain up to 100 units, depending of the values at each ...
0
votes
1answer
403 views
Generating control-point tangents for a Catmull-Rom spline
From Wikipedia, we have a few variations for calculating tangents when creating a spline based only on positions of control-points:
Finite difference
$$\mathbf m_k=\frac{\mathbf p_{k+1}-\mathbf ...
2
votes
1answer
40 views
Lower-Bounding angles in integer Lattices
Given an $n \times n$ integer grid I chose any two grid points $a,b$, draw a line $l$ through $a$ and $b$ and measure the angle between $l$ and a horizontal line. I can do this for any grid point pair ...
6
votes
3answers
365 views
How is it that this shape can converge to what looks like a triangle but has a different perimeter?
I had this strange notion some time ago, and I recently wrote a blog post about it, as a mere curiosity. I don't really consider it a "serious" mathematical question; but out of interest, I wondered ...
1
vote
1answer
189 views
How to get NURBS control points from an array of points that should be part of its solution from controll points we are searching for?
We are talking about Non-uniform rational B-spline. We have some simple 3 dimensional array like
{1,1,1}
{1,2,3}
{1,3,3}
{2,4,5}
{2,5,6}
{4,4,4}
Which are ...
