You’re most likely starting to sample the posterior distribution from a flat area. See this explanation of the algorithm behind mode_compute=6 and this post: Error: chol: input matrix must be positive definite - #2 by jpfeifer
You’re most likely starting to sample the posterior distribution from a flat area. See this explanation of the algorithm behind mode_compute=6 and this post: Error: chol: input matrix must be positive definite - #2 by jpfeifer