Linked Questions

42
votes
4answers
8k views

Fastest way to calculate matrix of pairwise distances

It is a very common problem that given a distance function $d(p_1,p_2)$ and a set of points pts, we need to construct a matrix ...
26
votes
6answers
8k views

Best way to create symmetric matrices

From time to time I need to generate symmetric matrices with relatively expensive cost of element evaluation. Most frequently these are Gram matrices where elements are $L_2$ dot products. Here are ...
14
votes
3answers
1k views

2D smoothing spline interpolation

Does Mathematica have 2D smoothing spline interpolation built in? I requires an interpolation method with smooth first derivatives and cubic bivariate splines fulfill this nicely. In python I would ...
10
votes
3answers
729 views

How can I speed up my compiled RBF interpolating function?

Overview I have a function that acts like the Interpolation on sparse $n$-dimensional data using a simple implementation of RBF interpolation method. I want my ...
8
votes
3answers
600 views

How can i construct a 3D surface pass through a curve defined by formula and some other controllable points?

For example, If a have a curve defined by x^2+y^2=1 and z=0, and some isolated points having z coordinates, Can I construct a 3D surface passed through? It's better if I can change the surface shape ...
6
votes
2answers
987 views

Plotting spherical surfaces

I am trying to make surface plots of squashed spheres. The spheres are defined by a list of points. For simplicity, consider the round sphere: ...
9
votes
2answers
478 views

Derivative of the Dedekind eta function fails to compute with errors I don't understand

When trying to understand better the question Eisenstein Series in Mathematica?, I stumbled on the following: issuing Derivative[1][DedekindEta][.11 I] gives ...
4
votes
2answers
549 views

Understanding polyharmonic splines

Rahul Narain and J.M. gives implementation of the thin plate polyharmonic splines in this post. Rahul Narain's method is clear. J.M.'s is convenient to reuse. But J.M. used too many matrix(ls,ws,lx,bb,...
2
votes
2answers
1k views

Interpolating and plotting a surface for a sparse set of 3d data points

I have a set of $(x,y,z)$ coordinates which sparsely cover a surface, e.g.: data = {{51, 15, 0.1}, {300, 11, 0.99}, {140, 22, 0.123}, {54, 12, 0.66}, ...}; What ...
4
votes
1answer
475 views

Interpolation of ListContourPlot3D, Volumetric data (cube file)

I know there are lots of information about this on stack exchange! Data interpolation and ListContourPlot InterpolationOrder for ContourPlot Unfortunately I was not able to find a proper way to ...
2
votes
1answer
158 views

Is there a reason why some specific arrangement of scattered grid points would yield bad RBF (Obtuse package) interpolation results?

I have an arrangement of grid points given by the figure below (the datagrid data is posted below at the end of the post): They correspond to electrode positions of an EEG signal. I am interpolating ...
1
vote
0answers
428 views

Smoothing ListContourPlot contours for unstructured grids. Part 2

My question is motivated by the following discussion. Smoothing ListContourPlot contours I need to generate high-quality contour plots for some property generated on a non-rectangular grid. This is ...
3
votes
1answer
130 views

Minimization with nongrid Interpolation function

I'm trying to minimize a complicated objective functional, which involves unstructured and unsmooth data on the backend of the functional evaluation. The real problem I'm trying to solve is a bit more ...
1
vote
0answers
114 views

Weighting ListContourPlot point distances

This is related to contour plot (cartesian) using spherical coordinates postions Dear friends, 1) I got the following contour, using: the data : [data]1 ...