% ISDIGIT ISDIGIT Test for Digit Characters in a String
% 
% Usage
% 
% The isdigit functions returns a logical array that is 1 
% for characters in the argument string that are digits, and 
% is a logical 0 for characters in the argument that are not
% digits.  The syntax for its use is
% 
%    x = isdigit(s)
% 
% where s is a string.  

function x = isdigit(s)
  s = int32(string(s));
  x = ((s >=48 ) & (s <= 57));