%N isdigitf %F $MIR/src/subs/match.for
%D Return true if char is 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9
%P bpw
%: strings
%B
      logical function isdigitf ( char )
      character*1 char

 isdigitf checks if the character char is a digit (0-9) and returns
 .true. if so, .false. if otherwise

 Input:
   char:    character to check
