Description Usage Arguments Value Author(s) References See Also Examples
Provide predictive mean, variance and covariance of a multi-fidelity cokriging model. 95 % confidence intervals are given based on Gaussian process assumption. This might be abusive in particular in the case where the number of observations is small.
1 2 3 |
object |
an object of class S3 ( |
newdata |
a vector, matrix or data frame containing the points where to perform predictions. |
type |
a list of character strings corresponding to the kriging family of the Gaussian processes δ_k(x) with k=1,...,nlevel (we use the convention δ_1(x) = Z_1(x)), to be chosen between simple kriging ( |
se.compute |
a list of optional booleans for each level. If |
cov.compute |
a list of optional booleans for each level. If |
checkNames |
a list of optional booleans for each level. If |
... |
no other argument for this method. |
mean |
multi-fidelity co-kriging predictive mean computed at |
sig2 |
multi-fidelity co-kriging predictive variance computed at |
C |
multi-fidelity co-kriging predictive conditional covariance matrix. Not computed if |
mux |
multi-fidelity co-kriging predictive means at each level. |
varx |
multi-fidelity co-kriging predictive variances at each level. |
CovMat |
multi-fidelity co-kriging predictive conditional covariance matrices at each level. |
Loic Le Gratiet
KENNEDY, M.C. & O'HAGAN, A. (2000), Predicting the output from a complex computer code when fast approximations are available. Biometrika 87, 1-13
FORRESTER, A.I.J, SOBESTER A. & KEAN, A.J. (2007), Multi-Fidelity optimization via surrogate modelling. Proc. R. Soc. A 463, 3251-3269.
LE GRATIET, L. & GARNIER, J. (2012), Recursive co-kriging model for Design of Computer Experiments with multiple levels of fidelity, arXiv:1210.0686
LE GRATIET, L. (2012), Bayesian analysis of hierarchical multi-fidelity codes, arXiv:1112.5389
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 | #--- test functions (see [Le GRATIET, L. 2012])
Funcf <- function(x){return(0.5*(6*x-2)^2*sin(12*x-4)+sin(10*cos(5*x)))}
Funcc <- function(x){return((6*x-2)^2*sin(12*x-4)+10*(x-0.5)-5)}
#--- Data
Dc <- seq(0,1,0.1)
indDf <- c(1,3,7,11)
DNest <- NestedDesign(Dc, nlevel=2 , indices = list(indDf) )
zc <- Funcc(DNest$PX)
Df <- ExtractNestDesign(DNest,2)
zf <- Funcf(Df)
#--- Multi-fidelity cokriging creation without parameter estimations
#--- "SK" : Simple CoKriging, i.e. when parameters are known
#--- "UK" : Universal CoKriging, i.e. when parameters are estimated
#-- model creation
mymodelSK <- MuFicokm(
formula = list(~1,~1),
MuFidesign = DNest,
response = list(zc,zf),
nlevel = 2,
coef.trend=list(0,2),
coef.rho=list(0.5),
coef.var=list(2,2),
coef.cov=list(0.1,0.2))
#-- predictions with "SK"
predictionsSK <- predict(
object = mymodelSK,
newdata = seq(0,1,le=100),
type = "SK")
#--- Multi-fidelity co-kriging building with parameter estimations
#-- model creation
mymodelUK <- MuFicokm(
formula = list(~1,~1),
MuFidesign = DNest,
response = list(zc,zf),
nlevel = 2)
#-- predictions with "UK"
predictionsUK <- predict(
object = mymodelUK,
newdata = seq(0,1,le=100),
type = "UK")
#--- Multi-fidelity co-kriging building with known and unknown parameters
#-- model creation
mymodelSK_UK <- MuFicokm(
formula = list(~1,~1),
MuFidesign = DNest,
response = list(zc,zf),
nlevel = 2,
coef.trend=list(-5,NULL),
coef.rho=list(NULL),
coef.var=list(2,NULL),
coef.cov=list(0.1,NULL))
#-- predictions with "UK"
predictionsSK_UK <- predict(
object = mymodelSK_UK,
newdata = seq(0,1,le=100),
type = list("SK","UK"))
#--- plot
op <- par(mfrow=c(3,1))
x <- seq(0,1,le=100)
curve(Funcf,ylim=c(-5,10),main="SK")
polygon(c(x,rev(x)), c(predictionsSK$mean+2*sqrt(predictionsSK$sig2),
rev(predictionsSK$mean-2*sqrt(predictionsSK$sig2))),
col="gray", border = "red",density=20 )
lines(seq(0,1,le=100), predictionsSK$mean,col=2,lty=2,lwd=2)
curve(Funcf,ylim=c(-5,10),main="UK")
polygon(c(x,rev(x)), c(predictionsUK$mean+2*sqrt(predictionsUK$sig2),
rev(predictionsUK$mean-2*sqrt(predictionsUK$sig2))),
col="gray", border = "red",density=20 )
lines(seq(0,1,le=100), predictionsUK$mean,col=2,lty=2,lwd=2)
curve(Funcf,ylim=c(-5,10),main="mix SK & UK")
polygon(c(x,rev(x)), c(predictionsSK_UK$mean+2*sqrt(predictionsSK_UK$sig2),
rev(predictionsSK_UK$mean-2*sqrt(predictionsSK_UK$sig2))),
col="gray", border = "red",density=20 )
lines(seq(0,1,le=100), predictionsSK_UK$mean,col=2,lty=2,lwd=2)
par(op)
|
Loading required package: DiceKriging
optimisation start
------------------
* estimation method : MLE
* optimisation method : BFGS
* analytical gradient : used
* trend model : ~1
* covariance model :
- type : matern5_2
- nugget : NO
- parameters lower bounds : 1e-10
- parameters upper bounds : 2
- best initial criterion value(s) : -30.18028
N = 1, M = 5 machine precision = 2.22045e-16
At X0, 0 variables are exactly at the bounds
At iterate 0 f= 30.18 |proj g|= 0.3502
At iterate 1 f = 30.111 |proj g|= 0.33614
At iterate 2 f = 30.042 |proj g|= 1.6348
At iterate 3 f = 30.034 |proj g|= 0.26938
At iterate 4 f = 30.033 |proj g|= 0.013115
At iterate 5 f = 30.033 |proj g|= 0.00011532
At iterate 6 f = 30.033 |proj g|= 4.8591e-08
iterations 6
function evaluations 8
segments explored during Cauchy searches 6
BFGS updates skipped 0
active bounds at final generalized Cauchy point 0
norm of the final projected gradient 4.85908e-08
final function value 30.0335
F = 30.0335
final value 30.033468
converged
optimisation start
------------------
* estimation method : MLE
* optimisation method : BFGS
* analytical gradient : used
* trend model : ~1
* covariance model :
- type : matern5_2
- nugget : NO
- parameters lower bounds : 1e-10
- parameters upper bounds : 2
- best initial criterion value(s) : -3.813998
N = 1, M = 5 machine precision = 2.22045e-16
At X0, 0 variables are exactly at the bounds
At iterate 0 f= 3.814 |proj g|= 0.00016814
At iterate 1 f = 3.814 |proj g|= 0.0001474
At iterate 2 f = 3.814 |proj g|= 5.3894e-05
At iterate 3 f = 3.814 |proj g|= 2.8356e-05
At iterate 4 f = 3.814 |proj g|= 1.3074e-05
At iterate 5 f = 3.814 |proj g|= 6.3667e-06
iterations 5
function evaluations 6
segments explored during Cauchy searches 5
BFGS updates skipped 0
active bounds at final generalized Cauchy point 0
norm of the final projected gradient 6.36673e-06
final function value 3.814
F = 3.814
final value 3.813998
converged
optimisation start
------------------
* estimation method : MLE
* optimisation method : BFGS
* analytical gradient : used
* trend model : ~1
* covariance model :
- type : matern5_2
- nugget : NO
- parameters lower bounds : 1e-10
- parameters upper bounds : 2
- best initial criterion value(s) : -4.732139
N = 1, M = 5 machine precision = 2.22045e-16
At X0, 0 variables are exactly at the bounds
At iterate 0 f= 4.7321 |proj g|= 0.226
At iterate 1 f = 3.814 |proj g|= 0
iterations 1
function evaluations 2
segments explored during Cauchy searches 1
BFGS updates skipped 0
active bounds at final generalized Cauchy point 1
norm of the final projected gradient 0
final function value 3.814
F = 3.814
final value 3.813998
converged
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