some people have requested RFF greta code - im not sure it works as i wrote it a while back and never tested it, but putting it here incase anyone is curious

Y=

X=

K=500 # number features

omega<-t(as.matrix(rnorm(K)))

library(greta)

tau<-exponential(1) # ridge penalty

bw<-gamma(1,1) # length scale

sigma<-gamma(1,1) # noise

W <- normal(0, 1, dim = c(2*K, 1)) tau*bw)

feat<-X%%(omega

rff<-sqrt(1/K)*cbind(sin(feat),cos(feat))
mu <- rff %*% W

distribution(Y) <- normal(mu, sigma)

model <- model(W, tau, bw)

draws <- mcmc(model, n_samples = 1000,control = list(Lmin = 10, Lmax = 20, epsilon = 1e-5))