online or on-line, straight line or straight-line

[vvujun]

Hi,

• This model is identified online (or on-line)?
• This model is built by using an online (or on-line) identification technique.
• The ship sails along a straight line (or straight-line).
• A straight line (or straight-line) tracking control method is proposed.

I am not sure if there are some differences between them.

Thanks for answering.
Jun

 

[sdgraham]

See this previous thread: online / on-line / on line

 

[Pertinax]

I would always use "online", though "on-line" is still common.
It's "straight line" as a noun (3), "straight-line" as an adjective (4).

 

[vvujun]

Dear adgraham and Pertinax, Thank you very much for your help.