how to make a diary on?

i've created 3 diaries on my matlab. they are: 1. rectangle 2. diary 3. myDiary. if i open matlab and start coding then in which diary my codes will be saved by default?

Answer 1

When you open Matlab, no diary is active. See:

get(0, 'Diary')
get(0, 'DiaryFile')

When you open several diaries, only the last one is used to log the activities in the command window.