First class:
1. How to enter matrices: A = [ 1 2; 3 4] or A = [1, 2; 3, 4] will enter
[ 1 2 ]
[ 3 4 ]
2. How to rref a matrix, method 1: rref(A), in this case it outputs:
[ 1 0 ]
[ 0 1 ]
3. How to rref a matrix using row elementary ops. First we start over
A = [1 2; 3 4]; //The last semi-colon silences the output. // starts a comment
// A(1,1) is already one, but normally we would need divide row1 by A(1,1)
// Make column 1 correct by make A(2,1) zero
A(2,:) = A(2,:) - 3*A(1,:) // r2 += -3r1
[ 1  2 ]
[ 0 -2 ]
// Make A(2,2) the next pivot
A(2,:) = A(2,:)/(-2) // r2 *= -2
[ 1 2 ]
[ 0 1 ]
// Make column 2 correct
A(1,:) = A(1,:) -2*A(2,:)
[ 1 0 ]
[ 0 1 ]
4. exec('iterate2d.in') // how to execute a command file.

Second class
1. The colon operator 4:7 outputs 4 5 6 7
2. The colom operator a:b:c starts with a, increments by b and stops before
getting bigger than c. a:c is the same as a:1:c.
2:3:9 outputs 2 5 8 (but not 11)
3. An empty range like 2:7:1 will ouput the empty matrix []
4. Colon as wild card (used is first class also)
A(:,2) is the second column of A
A(3,:) is the third row of A
5. We can combine things. A = [ 1 2 3 4 5; 5 6 7 8 9 ]
[ 1 2 3 4 5 ]
[ 5 6 7 8 9 ]
Then A(:, 2:4) is
[ 2 3 4 ]
[ 6 7 8 ]
6. The size operator, if B is a mxn matrix then size(B) returns
[ m n ]
So using the A from 5 above size(A) returns
[ 2 5 ]
and size(A(:, 2:4)) returns
[ 2 3 ]

Did we do for loops?
class3
1. elementwise operators
2. plotting