mesh_exsets: Search excursion set of nD function, sampled by a mesh

In DiceView: Methods for Visualization of Computer Experiments Design and Surrogate

Search excursion set of nD function, sampled by a mesh

Description

Search excursion set of nD function, sampled by a mesh

Usage

mesh_exsets(
  f,
  vectorized = FALSE,
  threshold,
  sign,
  intervals,
  mesh = "seq",
  mesh.sizes = 11,
  maxerror_f = 1e-09,
  tol = .Machine$double.eps^0.25,
  ex_filter.tri = all,
  ...
)

Arguments

f	Function to inverse at 'threshold'
vectorized	is f already vectorized ? (default: no)
threshold	target value to inverse
sign	focus at conservative for above (sign=1) or below (sign=-1) the threshold
intervals	bounds to inverse in, each column contains min and max of each dimension
mesh	function or "unif" or "seq" (default) to preform interval partition
mesh.sizes	number of parts for mesh (duplicate for each dimension if using "seq")
maxerror_f	maximal tolerance on f precision
tol	the desired accuracy (convergence tolerance on f arg).
ex_filter.tri	boolean function to validate a geometry::tri as considered in excursion : 'any' or 'all'
...	parameters to forward to mesh_roots(...) call

Examples

# mesh_exsets(function(x) x, threshold=.51, sign=1, intervals=rbind(0,1),
#   maxerror_f=1E-2,tol=1E-2) # for faster testing
# mesh_exsets(function(x) x, threshold=.50000001, sign=1, intervals=rbind(0,1),
#   maxerror_f=1E-2,tol=1E-2) # for faster testing
# mesh_exsets(function(x) sum(x), threshold=.51,sign=1, intervals=cbind(rbind(0,1),rbind(0,1)),
#   maxerror_f=1E-2,tol=1E-2) # for faster testing
# mesh_exsets(sin,threshold=0,sign="sup",interval=c(pi/2,5*pi/2),
#   maxerror_f=1E-2,tol=1E-2) # for faster testing

if (identical(Sys.getenv("NOT_CRAN"), "true")) { # too long for CRAN on Windows

  e = mesh_exsets(function(x) (0.25+x[1])^2+(0.5+x[2])^2 ,
                threshold =0.25,sign=-1, intervals=matrix(c(-1,1,-1,1),nrow=2),
                maxerror_f=1E-2,tol=1E-2) # for faster testing

  plot(e$p,xlim=c(-1,1),ylim=c(-1,1));
  apply(e$tri,1,function(tri) polygon(e$p[tri,],col=rgb(.4,.4,.4,.4)))

  if (requireNamespace("rgl")) {
    e = mesh_exsets(function(x) (0.5+x[1])^2+(-0.5+x[2])^2+(0.+x[3])^2,
                  threshold = .25,sign=-1, mesh="unif",
                  intervals=matrix(c(-1,1,-1,1,-1,1),nrow=2),
                  maxerror_f=1E-2,tol=1E-2) # for faster testing

    rgl::plot3d(e$p,xlim=c(-1,1),ylim=c(-1,1),zlim=c(-1,1));
    apply(e$tri,1,function(tri)rgl::lines3d(e$p[tri,]))
  }
}

DiceView documentation built on Jan. 17, 2023, 1:09 a.m.