ForK Library
Functions/Subroutines

krigingextremefuncpredictGEK.f90 File Reference

Subroutine to Predict mean function values from Gradient-Enhanced Kriging Surface (requires buildkrigingGEK to be called first)
Only Works for Ordinary Kriging (Constant Mean function) More...

Go to the source code of this file.

Functions/Subroutines

subroutine krigingextremefuncpredictGEK (ndim, ntot, X, gtot, pts, dims, stot, H, beta, V, hyper, Xm, Ym, covarflagi, optflag, flag, Lb, Ub)
 See documentation for krigingextremefuncpredict for details. This subroutine is the gradient-enhanced version and is functionally the same as the function-only subroutine.

Detailed Description

Subroutine to Predict mean function values from Gradient-Enhanced Kriging Surface (requires buildkrigingGEK to be called first)
Only Works for Ordinary Kriging (Constant Mean function)

Definition in file krigingextremefuncpredictGEK.f90.


Function Documentation

subroutine krigingextremefuncpredictGEK ( integer,intent(in)  ndim,
integer,intent(in)  ntot,
real(8),dimension(ndim,ntot),intent(in)  X,
integer,intent(in)  gtot,
integer,dimension(gtot),intent(in)  pts,
integer,dimension(gtot),intent(in)  dims,
integer,intent(in)  stot,
real(8),dimension(stot,ntot+gtot),intent(in)  H,
real(8),dimension(stot),intent(in)  Beta,
real(8),dimension(ntot+gtot),intent(in)  V,
real(8),dimension(ndim+3),intent(in)  hyper,
real(8),dimension(ndim),intent(out)  Xm,
real(8),intent(out)  Ym,
integer,intent(in)  covarflagi,
integer,intent(in)  optflag,
integer,intent(in)  flag,
real(8),dimension(ndim),intent(in)  Lb,
real(8),dimension(ndim),intent(in)  Ub 
)

See documentation for krigingextremefuncpredict for details. This subroutine is the gradient-enhanced version and is functionally the same as the function-only subroutine.

Author:
Brian Lockwood Department of Mechanical Engineering University of Wyoming
Date:
May 2, 2012
Parameters:
in)ndim : The dimension of the problem
in)ntot : The number of Training points
in)X : The location of the training points (size=[ndimxntot])
in)gtot: Number of derivative values included in training data (ndim*ntot if all derivatives are included at the training points)
in)pts: List identifying what point the derivative value is enforced at (size=[gtot] with values ranging from 1 to ntot)
in)dims: List identifying the dimension the derivative is taken with respect to (size=[gtot] with values ranging from 1 to ndim)
in)stot : Number of Terms in the regression
in)H: The collocation matrix for the regression including derivative values. (size=[stotxntot+gtot])
Columns 1:ntot are the basis evaluated at the training points
Columns ntot+1:ntot+gtot are the derivative of the basis evaluated at the training points
in) beta: Regression coefficients based on the optimal estimate for the Kriging model (size=[stot])
Supplied by buildkrigingGEK subroutine
in)V: Processed Training Data (size=[ntot+gtot])
Supplied by buildkrigingGEK subroutine
in)hyper: Hyperparameters for the Kriging Model (size=[ndim+3])
Supplied by buildkrigingGEK subroutine
out) Xm : Location of the extreme point (size=[ndim])
out) Ym : Minimum or Maximum value
in)covarflagi: Flag to govern which covariance function is used

  • covarflag==1 Uses Matern function with \(\nu=3/2\)
  • covarflag==2 Uses Matern function with \(\nu=5/2\)


The parameter \(\nu\) governs the smoothness and differentiability of the covariance function.
When using gradient values, \(\nu=1/2\) is not differentiable enough so \(\nu \geq 3/2\) must be used
Must supply the same covariance flag as used in buildkrigingGEK.

in)optflagi: Flag to govern the optimization algorithm used to determine minimum or maximum value

  • optflag=0 Simplex Search (Nelder-Mead Method) to determine extreme value
    Local optimization technique using simplex elements to determine search direction and line search to determine step sizes
    Fastest method but inherently sequential and may stall on local optimum
  • optflag=1 Pattern Search used to determine extreme value
    Global optimization method with fixed search directions (forward and backward in each direction)
    Each iteration requires \(2*ndim\) function evaluations; however, these may be performed in parallel using openmp (Each thread performs own likelihood evaluation so OMP_STACK_SIZE must be set large enough)
in) flag Determines whether minimum or maximum value is found

  • flag = 0 Subroutine finds the minimum value
  • flag = 1 Subroutine finds the maximum value
in) Lb Lower Bound for each variable (size = [ndim])
Should be the minimum possible value of Xm in each dimension
in) Ub Upper Bound for each variable (size = [ndim])
Should be the maximum possible value of Xm in each dimension

Definition at line 61 of file krigingextremefuncpredictGEK.f90.

References patternsearch(), and simplexsearch().

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