similar to: Concentration ellipsoid

Hello, in a three dimensional coordinate system, I'd like to find all my experimental data points that fall within an ellipsoid around a fixed coordinate. The fixed point is defined by (x.coord.point, y.coord.point, z.coord.point). The coordinates of the ellipsoid are given by the three vectors x,y,z. In a previous version of my code, I simply used a box instead of an ellipsoid to sort

+ Hello, The parametric equations of an ellipsoid can be written in terms of spherical coordinates. The three spherical coordinates are converted to Cartesian coordinates by X=a cos (α) sin(θ) Y=b sin(α) sin(θ) Z=c cos(θ) for α and θ The parameter α varies from 0 to 2 π and θ varies from 0 to π . Here ( X o , Y o ,Z o ) is the center of the ellipsoid, and θ is the angle

I have a 3xN matrix of parameters obtained from N regressions where the 3 parameters are jointly statistically significant. I would like to reproduce a 3D confidence ellipsoid projecting 2D ellipses onto the XY plane as in Figure 5.2 in this

Hey, all I am going to plot several 3-dimensional ellipsoids in R. For example, A is such a ellipsoid with mean u=[1 1 1]', covariance matrix C=[1 0 .5;0 1 .6;.5 .6 1]; So how can I plot such object in 3D space? Is there some function to achieve this? Thanks. Fred

John Fox wrote: >The confidence ellipse for a pair of coefficients is just (with an >adjustment for size) the perpendicular shadow of the joint ellipsoid, in >the same sense that the confidence intervals for individual coefficients >are shadows of the joint ellipsoid or ellipse. The usual confidence ellipse >for 2 of q coefficients uses qf(.95, 2, df.error) to scale the ellipse; if

Dear All, The Minimum Volume Ellipsoid estimator ("cov.mve") was part of S+ but I cannot find it in R. Where can I find it? Why was it excluded? Cheers, Patrik Sweden

I am interested in making a random sample from a uniform distribution of points over the surface of the earth, using the WGS84 ellipsoid as a model for the earth. I know how to do this for a sphere, but would like to do better. I can supply random numbers, want latitude longitude pairs out. Can anyone point me at a solution? Thanks very much. -- Russell Senior ``I have nine fingers;

Dear all, Has anyone written functions to compute (and ideally project / plot onto a plane) confidence ellipsoids for q linear model parameters, q > 2 ? Greetings and best wishes, Renaud -- Dr Renaud Lancelot, v?t?rinaire CIRAD, D?partement Elevage et M?decine V?t?rinaire (CIRAD-Emvt) Programme Productions Animales http://www.cirad.fr/presentation/programmes/prod-ani.shtml ISRA-LNERV

In the 'doBy' package there is an esticon() function for calculating linear contrasts for various model types. I have defined an S3-method 'esticon.mer()' for 'mer' objects from the lme4 package. Building the package and invoking the method gives: > esticon(fm1, c(1,1)) Confidence interval ( WALD ) level = 0.95 Error in as.integer(x) : cannot coerce type 'S4'

Hello, I'm working with a series (30+) of hydrologic metrics and 10 vegetation communities and I need to determine which of the metrics provide the best separability for each of the vegetation communities. The hydrologic metrics are highly correlated, therefore the need to reduce the number of them considered is critically important. I've been looking at the scatter3d function in the

Dear list, I'm trying to visualise some ellipsoidal shapes in 3D. Their position, axes, and angular orientation can be arbitrary. I saw an ellipse3d function in rgl; however it is heavily oriented towards the statistical concept of ellipse of confidence, whilst I am just concerned with the geometrical object. Below is my current implementation. It is quite slow when creating many shapes, so

Hi, I am trying to replicate the R's result for VCV matrix of estimated coefficients from linear model as below data(mtcars) model <- lm(mpg~disp+hp, data=mtcars) model_summ <-summary(model) MSE = mean(model_summ$residuals^2) vcov(model) Now I want to calculate the same thing manually, library(dplyr) X = as.matrix(mtcars[, c('disp', 'hp')] %>% mutate(Intercept =

I am curious if there is code developed to plot confidence regions in 3D. The scatterplot3d function generates the plot I want, but would like an 3D equivalent to the data.ellipse function. Any help in this direction would be appreciated, be it theoretical, graphical, or otherwise. Melanie Edwards Senior Statistician Exponent 15375 SE 30th PL, Suite 250 Bellevue, WA 98007 Tel: (425) 519-8714

Hi all, How do I visualize a contour of a tri-variate normal distribution? I just like to see the ellipsoid very much. I hope there is a easy way or existing method in R. Thank you a lot! Michael. [[alternative HTML version deleted]]

sigma(model)^2 will give the correct MSE. Also note that your model matrix has intercept at the end whereas vcov will have it at the beginning so you will need to permute the rows and columns to get them to be the same/ On Wed, Sep 4, 2024 at 3:34?PM Daniel Lobo <danielobo9976 at gmail.com> wrote: > > Hi, > > I am trying to replicate the R's result for VCV matrix of

For a paper dealing with generalized ellipsoids, I want to illustrate in 3D an ellipsoid that is unbounded in one dimension, having the shape of an infinite cylinder along, say, z, but whose cross-section in (x,y) is an ellipse, say, given by the 2x2 matrix cov(x,y). I've looked at rgl:::cylinder3d, but don't see any way to make it accomplish this. Does anyone have any ideas? thx,

Dear all, I would like to draw a 3-D horizontal cylinder preferably in RGL device (because this gives the look from different angles). Basic idea is from http://www.tau.ac.il/cc/pages/docs/sas8/insight/chap18/sect3.htm. Below is the description exactly what I want to do. Please see at figure 18.6, 1st plot. Here it is an confidence ellipsoid. Suppose now you put another 4 same ellipsoids on top

Hi, does anyone know how to plot 3D parametric surface,e.g ellipsoid: x=a*cos(s)*cos(t), y=b*sin(s)*cos(t), z=sin(t); s in [0,2*pi], t in [-pi,pi]. Vytautas Maniusis, Vilnius University, Lithuania

I think vcov() gives estimates of VCV for coefficients. I want estimate of SD for residuals On Tue, Dec 24, 2024 at 7:24?PM Ben Bolker <bbolker at gmail.com> wrote: > > vcov(). ? > > > On Tue, Dec 24, 2024, 8:45 AM Christofer Bogaso <bogaso.christofer at gmail.com> wrote: >> >> Hi, >> >> I have below GLM fit >> >> clotting <-

Dear list, I've generated a list of 3D coordinates representing ellipsoids in arbitrary orientations. I'm now trying to obtain a 2D projection of the scene, that is to draw the silhouette of each object on a plane (x,y). The only way I could think of is to compute the convex hull of the (x,y) coordinates of each object and use this as the outline of the object. This is clearly