Clarify tri input is unused in dsearch, change griddata to dsearchn (…

…bug #66760).

* dsearch.m, dsearchn.m: Add note to docstring that tri input is unused for
dsearch calculation.

* griddata: Change internal dsearch call to a dsearchn call.

scripts/geometry/dsearch.m

@@ -29,7 +29,9 @@
 ## Return the index @var{idx} of the closest point in @code{@var{x}, @var{y}}
 ## to the elements @code{[@var{xi}(:), @var{yi}(:)]}.
 ##
-## The variable @var{s} is accepted for compatibility but is ignored.
+## The variables @var{s} and @var{tri} are accepted for compatibility, but they
+## are not used in the calculation or checked for validity.
+##
 ## @seealso{dsearchn, tsearch}
 ## @end deftypefn
 

scripts/geometry/dsearchn.m

@@ -38,6 +38,13 @@
 ## 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{dsearch, tsearch}
 ## @end deftypefn
 

scripts/geometry/griddata.m

@@ -196,7 +196,7 @@
 
     elseif (strcmp (method, "nearest"))
       ## Search index of nearest point.
-      idx = dsearch (x, y, tri, xi, yi);
+      idx = dsearchn ([x(:), y(:)], tri, [xi(:), yi(:)]);
       valid = ! isnan (idx);
       zi(valid) = z(idx(valid));