Scale Invariant Probabilistic Neural Networks R package spnn version 1.3.0 Scale invariant version of the original PNN proposed by Specht (1990) <doi:10.1016/0893-6080(90)90049-q> with the added functionality of allowing for smoothing along multiple dimensions while accounting for covariances within the data set. It is written in the R statistical programming language. Given a data set with categorical variables, we use this algorithm to estimate the probabilities of a new observation vector belonging to a specific category. This type of neural network provides the benefits of fast training time relative to backpropagation and statistical generalization with only a small set of known observations. Software Imports: MASS (>= 3.1-20), Rcpp (>= 1.0.0) LinkingTo: Rcpp, RcppArmadillo Romin Ebrahimi <romin.ebrahimi@utexas.edu> Comprehensive R Archive Network (CRAN) Romin Ebrahimi [aut, cre] GPL (>= 2) 2025-10-20 application/tgz https://CRAN.R-project.org/package=spnn doi:10.32614/CRAN.package.spnn