# save as sublog.pl
# demonstrates subroutines
# calculates logarithm
print "Calculator for LOG of X to base B\n";
print "Enter X: "; $x=<STDIN>;
print "Enter B: "; $b=<STDIN>;
printf("%s%.4f\n", "The result is ", callog($x,$b));

sub callog{
  my($val,$base)=@_;
  return (log($val)/log($base));
  }