%N isalphaf %F $MIR/src/subs/match.for
%D Return true if char is a letter (a-z, A-Z)
%P bpw
%: strings
%B
      logical function isalphaf ( char )
      character*1 char

 Isalphaf checks if the character char is a letter (a-z or A-Z)
 and returns .true. if so, .false. if otherwise

 Input:
   char:    character to check
