the way I learned it was j...
unfortunatly I finished my homework some years ago...
the reason it's i to you is because you're a mathematition, (pure maths, simply on paper has (IMO) no real use,)
case: I have a friend who studied math, went onto do higher math, and then went to university and got his degree in math... and the point of all this math? well he's no a math teacher!!!
The reason is is j as far as I'm concerned is because I learned whilst studying math at Uni for an electronic engineering course.
i already has a standard meaning to electronic engineers, (current).
so we use the letter j instead.