Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help ft_debug”.

  FT_DEBUG prints a debug message on screen, depending on the verbosity 
  settings of the calling high-level FieldTrip function.
 
  Use as
    ft_debug(...)
  with arguments similar to fprintf, or
    ft_debug(msgId, ...)
  with arguments similar to warning.
 
  You can switch of all messages using
    ft_debug off
  or for specific ones using
    ft_debug off msgId
 
  To switch them back on, you would use 
    ft_debug on
  or for specific ones using
    ft_debug on msgId
  
  Messages are only printed once per timeout period using
    ft_debug timeout 60
    ft_debug once
  or for specific ones using
    ft_debug once msgId
 
  You can see the most recent messages and identifier using
    ft_debug last
 
  You can query the current on/off/once state for all messages using
    ft_debug query
 
  See also FT_ERROR, FT_WARNING, FT_NOTICE, FT_debug, FT_DEBUG, ERROR, WARNING