Questions tagged [cholesky-decomposition]
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96 questions
0 votes
0 answers
32 views
Generated correlation random numbers with arbitrary, non-identically distriubuted distributions
I have a dataset from which I need to construct priors from which to draw vectors of correlated but non-identically distributed random samples. For the sake of example, suppose I have $n$ lognormal ...
1 vote
0 answers
76 views
Cholesky ACE model (genetics modelling) with ordinal variable
Posting here as I've been tasked with running ACE models for a twins analysis project I'm working on. ACE models refer to a form of structural equation analysis that seeks to to partition phenotypic ...
0 votes
0 answers
45 views
How to shock a VAR Model? Effect of interest rate change on Gini
I’m currently working on a VAR model to analyze the impact of expansionary monetary policy on inequality. The inequality measure is Gini and I control for macroeconomics variables such as GDP and ...
0 votes
0 answers
73 views
Does a normal matrix have a "very fast" inverse after doing cholesky?
If the decomposition of a normal matrix is positive definite, and it's clearly also a square matrix, and each decomposition $L$ is square; it seems that one could invert the result fast, but since I'm ...
1 vote
0 answers
55 views
INDSCAL as a special case of CANDELINC
Here is my attempt to show that INDSCAL as a special case of CANDELINC. I am using the following paper as my reference for definitions. Kolda, Tamara G., and Brett W. Bader. "Tensor ...
2 votes
0 answers
62 views
Cholesky factorization of a conditional multivariate normal distribution
Let $X$ be a random vector with multivariate normal distribution: $X\sim \mathcal{N}(\mu,\Sigma)$. Let $L$ be the Cholesky factorization of $\Sigma$: $\Sigma = LL'$, so that we can write $$X=L X_0 +\...
6 votes
1 answer
420 views
Sampling with specified covariance matrix and distribution
Given a positive semi-definite $n\times n$ matrix $C$ I would like to construct $n$ random variables $X_1,\dots,X_n$ drawn from $n$ fixed distributions such that $\mathrm{corr}(X_i,X_j) = C_{ij}$. I ...
2 votes
1 answer
190 views
Passing a cholesky decomposition for a matrix with constrained variances to an objective function
I am trying to optimize an objective function $L(\theta)$ in which some parameters that I aim to recover belong to a covariance matrix, $\Sigma$. $\Sigma$ has a unique structure, which includes ones ...
4 votes
0 answers
333 views
Fast Cholesky decomposition of a Toepllitz matrix via embedding in a circulant & fft
As I understand it, the Cholesky decomposition of a Toeplitz matrix can be computed more efficiently by first embedding it in a circulant matrix then using FFT, but I'm having trouble finding any ...
0 votes
0 answers
133 views
Efficient way to encode a set of large covariance matrices
I have a computational model that involves having a set of $K$ covariance matrices, $\{\Sigma_1, ..., \Sigma_K\}$ with each $\Sigma_i \in R^{n \times n}$. Storing all these full covariance matrices is ...
2 votes
1 answer
651 views
How to sample efficiently from an inverse Wishart distribution?
I am trying to understand the code from pybasicbayes, which defines the following function to sample from an inverse Wishart: ...
1 vote
1 answer
171 views
Interpretation of impulse response analysis - Cholesky decomposition output in R
I am doing an impulse response analysis involving 3 time series A, B, and C in R. Following Lutkepohl approach, I used the log and diff functions to make them stationary. After creating the VAR model, ...
1 vote
0 answers
59 views
General matrix decomposition downgrading algorithm for sampling
I would like to sample from a multivariate Gaussian distribution with covariance matrix $\Sigma - uu^T $, where $u$ is a vector and $\Sigma - uu^T $ is PSD. I have knowledge of a non-Cholesky ...
2 votes
1 answer
239 views
Spectral decomposition and quadratic forms
Let $\mathbf{x}\sim N(0,I)$ and $A$ a real-valued square matrix. The spectral decomposition allows us to rewrite a quadratic form $\mathbf{x}^\top A \mathbf{x}$ as a sum of iid chi-squared random ...
8 votes
1 answer
1k views
Statistical interpretation of diagonal of Cholesky decomposition?
Given a set of $m$ examples $x$ arranged as rows in $m\times n$ data matrix X, consider Cholesky decomposition of covariance matrix $X'X$. Is there a statistical interpretation of diagonal entries of ...