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##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
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## -*- texinfo -*-
## @deftypefn  {} {@var{idx} =} dsearchn (@var{x}, @var{tri}, @var{xi})
## @deftypefnx {} {@var{idx} =} dsearchn (@var{x}, @var{tri}, @var{xi}, @var{outval})
## @deftypefnx {} {@var{idx} =} dsearchn (@var{x}, @var{xi})
## @deftypefnx {} {[@var{idx}, @var{d}] =} dsearchn (@dots{})
## Return the index @var{idx} of the closest point in @var{x} to the elements
## @var{xi}.
##
## If @var{outval} is supplied, then the values of @var{xi} that are not
## contained within one of the simplices @var{tri} are set to @var{outval}.
## Generally, @var{tri} is returned from @code{delaunayn (@var{x})}.
##
## The optional output @var{d} contains a column vector of distances between
## the query points @var{xi} and the nearest simplex points @var{x}.
##
## Compatibility note: The @code{dsearchn} algorithm only uses the input
## @var{tri} when @var{outdim} is specified to determine if any points lie
## outside of the triangulation region.  For compatibility, @var{tri} is
## accepted as an input even when @var{outdim} is not specified, but it is not
## used or checked to be a valid triangulation, and providing it will not
## affect either the output @var{idx} or the calculation efficiency.
##
## @seealso{tsearchn, delaunayn}
## @end deftypefn

function [idx, d] = dsearchn (x, tri, xi, outval)

  if (nargin < 2)
    print_usage ();
  endif

  if (nargin == 2)
    [idx, d] = __dsearchn__ (x, tri);
  else
    [idx, d] = __dsearchn__ (x, xi);
    if (nargin == 4)
      idx2 = isnan (tsearchn (x, tri, xi));
      idx(idx2) = outval;
      d(idx2) = outval;
    endif
  endif

endfunction


%!shared x, tri
%! x = [-1,-1;-1,1;1,-1];
%! tri = [1,2,3];
%!assert (dsearchn (x,tri,[1,1/3]), 3)
%!assert (dsearchn (x,tri,[1,1/3],NaN), NaN)
%!assert (dsearchn (x,tri,[1,1/3],NA), NA)
%!assert (dsearchn (x,tri,[1/3,1]), 2)
%!assert (dsearchn (x,tri,[1/3,1],NaN), NaN)
%!assert (dsearchn (x,tri,[1/3,1],NA), NA)
