A mixing time bound for Gibbs sampling from log-smooth log-concave distributions

Abstract: The Gibbs sampler, also known as the coordinate hit-and-run algorithm, is a Markov chain that is widely used to draw samples from probability distributions in arbitrary dimensions. At each iteration of the algorithm, a randomly selected coordinate is resampled from the distribution that results from conditioning on all the other coordinates. We study the behavior of the Gibbs sampler on the class of log-smooth and strongly log-concave target distributions supported on $\mathbb{R}^n$. Assuming the initial distribution is $M$-warm with respect to the target, we show that the Gibbs sampler requires at most $O^{\star}\left(\kappa^2 n^{7.5}\left(\max\left{1,\sqrt{\frac{1}{n}\log \frac{2M}{\gamma}}\right}\right)^2\right)$ steps to produce a sample with error no more than $\gamma$ in total variation distance from a distribution with condition number $\kappa$.