Exercises 1.8 Homework
1.
Suppose that A
is a matrix. Describe, in words, the following objects:
A(3, :)
A(:, end-2)
A(1:2, end-1:end)
A(1:2:end, 1)
A(:, end:-1:1)
2.
Write a script to do the following:
x = (first 5 digits of your SUID); y = (all entries of x except first); z = (all entries of x except last); u = (the sum of vectors y and z); v = (the scalar product of vectors y and z, also known as the dot product in Calculus);
Then display u
and v
using disp
.
Note that y
and z
must be computed from the vector x
, not entered number-by-number.
3.
Write a script that does the following:
- Let
A
be some 3 by 3 matrix filled with numbers 1,2,…,9 - Let
x
be the product ofA
and a row vector with all entries equal to 1 (think about the correct order of multiplication). - Let
y
be the product ofA
and a column vector with all entries equal to 1.
When uploading your script to Blackboard, leave a comment with answers to the following questions:
- What is the meaning of the entries of
x
? In other words, what information aboutA
do we get from the entries ofx
? - What is the meaning of the entries of
y
?
Hint
Both x and y represent certain sums.