Questions tagged [local-coordinates]

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3
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1answer
84 views

How avoid square shape with Laplacian operator in reaction diffusion calculations?

I have used different variants of the Laplacian operator (div grad) using 4, 8, 12, 20 and 24 of the closest points. I get problems due to the chosen coordinate system and the discretization of the ...
2
votes
1answer
55 views

Using linear regression to find the ideal point given a set of trajectory's data

I have a set of points in 2D obtained from a pendular movement with some noise. I want to determine where is equilibrium point ($x_0$, $y_0$) from which the rope is fixed. There are at least two ...
0
votes
0answers
28 views

Normalized Coordinate system, Hermitian Cubic Shape function

How can I convert a local shape function given in terms of normalized/natural coordinates to global shape function in terms of x and y coordinate system in Hermitian cubic shape function. Please ...
2
votes
0answers
68 views

1-D local interpolation of sampled function that is polynomial in 1/x

I have a number of evenly-spaced samples of functions that are polynomial in $1/x$ where $x$ is a continuous variable on $x\in\left[a,b\right]$, i.e. $$f(x_i)=\sum_{n=0}^{N} f_n x_i^{-n}.$$ I want to ...
4
votes
1answer
2k views

Unwrap cylinder to plane in Paraview

I want to extract the data from the boundary surface of a cylinder (in a .vtu file) and plot it onto a plane, where the coordinates are theta (rotation angle) and Z(...
4
votes
1answer
174 views

How to express the derivatives with respect to the initial coordinates {x,y,z} when 3D coordinate system is mapped into 2D manifold {e,n}?

This is often required in the stiffness matrix evaluation. Thanks to this thread I found out how to perform integrals over 2D surface. I've tried to evaluate the integral of the single shape function ...
5
votes
2answers
291 views

changing from global to local coordinate structure

I am going to put this question on math exchange and stack exchange as well (since it doesn't really fit in any of the specific fields, I don't know which it should go in), but here is the question: ...