guide for midterm 2:

1. review previous quiz.

2. What is rank of a matrix? How to compute it?
3. How to compute the coordinate of a vector with respect
   to a given basis?
4. Given the coordinate of a vector with respect to a given basis E,
   How to compute the coordinate with respect to another given basis F?
4. Given the matrix representation of L with respect to E,
   How to compute its representation with respect to F?
5. Given the description of a linear transformation,
   (eg. rotation, dilation, reflection), 
   How to write down its matrix representation?