How abou the following?
(In this script, I have used shape file provided in http://thematicmapping.org/downloads/world_borders.php)
% Load shape file of country border
S = shaperead('TM_WORLD_BORDERS_SIMPL-0.3.shp');
S = struct2table(S);
% Target lat and lon (e.g Tokyo)
lat = 35.7;
lon = 139.7;
% Find which country contains (lat,lon)
idx = cellfun(@(X,Y) inpolygon(lon,lat,X,Y),S.X, S.Y);
% Show the result
disp(S.NAME(idx))
>> disp(S.NAME(idx))
'Japan'
