• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Math Help

Status
Not open for further replies.

shermaine

New Member
Given:

X = [ 1 1
1 1.5
1 3
1 3.5
1 4]

d = [ 3.5
2.5
2
1
1]

how do i get w = [X^T (X)]^-1 (X^T) d

The ans is [ 4.04
- 0.78]

I tried, but i cant the answer.
Can anyone advise me
Thanks.
 

MrAl

Well-Known Member
Most Helpful Member
Hi,

You must know a few things in order to solve this:

1. How to multiply matrixes and vectors.
2. How to compute the transpose of a matrix.
3. How to find the inverse of a matrix.


If you do not know how to do any of the above let us know.

If you do, then you proceed as follows:

1. Calculate the transpose of X, call this T.
2. Calculate T*X in that order using vector/matrix multiplication, call the result Y.
3. Find the inverse of Y (which is Y^-1), call that I.
4. Multiply I*T, call that S.
5. Finally, multiply S*d and that result is the answer which is approximately:
[4.037313433,
-0.783582090]

Remember that when you do matrix multiplication you have to observe the correct order as you
can not reverse the order like you can do with regular single number arithmetic multiplication like
2*3=6.
 
Last edited:
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top