def get_textual_float(value, format = '%.2f'):
    """Get textual representation of floating point numbers
    and accept None as valid entry

    format is a string - default = '%.2f'
    """

    if value is None:
        return 'None'
    else:
        try:
            float(value)
        except:
            # May this is a vector
            if len(value) > 1:
                s = '('
                for v in value:
                    s += get_textual_float(v, format) + ', '
                    
                s = s[:-2] + ')' # Strip trailing comma and close
                return s
            else:
                raise Exception('Illegal input to get_textual_float: %s' % str(value))
        else:
            return format % float(value)