R package stilt. Functions to build and use an interpolator (”emulator”) for time series or 1D regularly spaced data in multidimensional space. The standard usage is for interpolating time-resolved computer model output between model parameter settings. It can also be used for interpolating multivariate data (e.g., oceanographic time-series data, etc.) in space. There are functions to test the emulator using cross-validation, and to produce contour plots over 2D slices in model input parameter (or physical) space.