My date on Valentine's Day

Wahaha

I have a date on valentine's day!
She's smart, intriguing and full of figures
Some people like her, some people hate her
Me?
I have a love-hate relartionship with her
Love her when she's being practical
Hate her when she's being theoretical
I've spent the whole summer with her
Sometimes even slogging through night with her when there are tests coming
Guess who she is?

First person to get it correct gets something from me!