## hetGP 1.1.8
  * add an update_pred function for prediction update formulas
  * add gradient of logEI function
  * average then log-transform empirical variances in hetGP initialization, thanks to P. Vijay
  * add batch BO loops with qEI and a qHSRI

## hetGP 1.1.7
  * Add plot method for CRNGP
  * Add logEI optimization criterion
  * Clarify internal derivatives
  * Fix some NOTE issues

## hetGP 1.1.6
  * Add new GP model allowing for common random numbers
  * Fix some sign problems in derivatives with Matern3_2
  * Avoid some name propagations in internal functions
  
## hetGP 1.1.5
  * bug corrections
  * modify class checks

## hetGP 1.1.4
  * add JSS article CITATION file
  * add citation in DESCRIPTION and some .Rd files

## hetGP 1.1.3
  * update vignette
  * new fonction to predict at noisy inputs: pred_noisy_input
  * update references
  * bug corrections (mclapply in IMSPE_search)
  * add fast (approximated) batch Expected Improvement

## hetGP 1.1.2

## change / hetGP 1.1.1
  * arguments factr and pgtol can now be passed to optim via settings
  * prevent optim from returning values not strictly inside [0,1] with IMSPE
  * update contour functions: MCU is now MEE, a new MCU is defined following updates in the paper
  * parallel computation with mclapply available with IMSPE_optim and crit_optim
  * add predictive variance to plot method
  * add score function
  * new 1d test function + noisy versions
  * add generic loglikelihood function
  * update vignette
  
## hetGP 1.1.1

## change / hetGP 1.1.0
  * add vignette describing the package
  * precisions on noise.var with predict.hetGP in the documentation
  * change print method to return summary
  * add plot methods to GP and TP models
  * catch optim errors when at least one likelihood evaluation worked
  * lower and upper are now optional parameters
  * IMSPE include the extra term with estimated beta0 (but not crit_IMSPE at this stage)
  * IMSE.search and IMSE_nsteps_ahead are now a single function: IMSPE_optim
  * update defaults of IMSE.search
  * new functions crit_optim mimicking IMSPE_optim for contour/optim criteria
  * catch numerical errors in updated variance in contour criteria
  * improve partial derivatives wrt theta for Matern kernels
  * add time slot in model fitting outputs
  * faster trace computations in the symmetric case
  * initial theta values when providing lower and upper is now 10% of the range
  * fix strip and crit_EI methods (thanks to Rob Smith)

## hetGP 1.1.0

## change / hetGP 1.0.2
  * better handling of the penalty term
  * update the documentation, rename nu2_hat by nu_hat for consistency with JCGS paper
  * several performance improvements (e.g., predict with xprime argument)
  * contour finding infill criteria related to arXiv:1807.06712
  * add Expected Improvement criterion (beta version)
  * correct bug with known mean not used for initialization with mleHetGP/TP
  * add leave one out predictions

## hetGP 1.0.2

## change / hetGP 1.0.1
  * homTP/heTP update methods
  * option settings$return.hom to return or not modHom models with hetGP and hetTP
  * new functions to export/import hetGP objects, including a robust re-computation of inverse covariance matrices
  * accordingly, predict now only threshold negative predictive variances occuring due to numerical instability with Cholesky inverse
  * better initialization with mleHetTP
  * improved warnings and error handling

## hetGP 1.0.1

## change / hetGP 1.0.0
  * add Student-t modeling (equivalent of mleHetGP and mleHomGP, with predict functions)
  * various typos and bugs corrections
  * now works on Solaris
  