# emulator v1.2-20

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## Bayesian Emulation of Computer Programs

Allows one to estimate the output of a computer program, as a function of the input parameters, without actually running it. The computer program is assumed to be a Gaussian process, whose parameters are estimated using Bayesian techniques that give a PDF of expected program output. This PDF is conditional on a training set of runs, each consisting of a point in parameter space and the model output at that point. The emphasis is on complex codes that take weeks or months to run, and that have a large number of undetermined input parameters; many climate prediction models fall into this class. The emulator essentially determines Bayesian posterior estimates of the PDF of the output of a model, conditioned on results from previous runs and a user-specified prior linear model. A vignette is provided and the help pages include examples.

## Functions in emulator

 Name Description regressor.basis Regressor basis function results.table Results from 100 Goldstein runs makeinputfiles Makes input files for condor runs of goldstein optimal.scales Use optimization techniques to find the optimal scales pad Simple pad function model Simple model for concept checking sigmahatsquared Estimator for sigma squared scales.likelihood Likelihood of roughness parameters interpolant Interpolates between known points using Bayesian estimation OO2002 Implementation of the ideas of Oakley and O'Hagan 2002 estimator Estimates each known datapoint using the others as datapoints s.chi Variance estimator prior.b Prior linear fits sample.n.fit Sample from a Gaussian process and fit an emulator to the points quad.form Evaluate a quadratic form efficiently toy A toy dataset tr Trace of a matrix latin.hypercube Latin hypercube design matrix expert.estimates Expert estimates for Goldstein input parameters emulator-package emulator betahat.fun Calculates MLE coefficients of linear fit corr correlation function for calculating A No Results!