What Does X'X Represent in Linear Algebra?

  • Thread starter Thread starter RufusDawes
  • Start date Start date
  • Tags Tags
    Mean
Click For Summary
In linear algebra, X'X represents the product of a matrix X transposed and the matrix X itself, often denoted as XTX. This expression is significant in statistics, particularly in relation to sums of squares and cross-product matrices. The discussion highlights its relevance in understanding deviations in data analysis. The concept of transposition is crucial for matrix operations and transformations. Overall, X'X plays a vital role in various mathematical and statistical applications.
RufusDawes
Messages
154
Reaction score
0
What does X'X mean ?
 
Physics news on Phys.org
Apparently it has something to do with a matrix.
 
In linear algebra, ' is often used to indicate Transpose. So X'X = XTX.
 

Thread 'Distance between a Clock's hands when the distance is increasing most rapidly'

Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?
View full post »

Similar threads

What does a row matrix represent geometrically?
  • · Replies 8 ·
Replies
8
Views
1K
Mean of L2 norm of random vector Ax+n
  • · Replies 3 ·
Replies
3
Views
2K
Question about hat matrix X(X'X)^(-1)X'
  • · Replies 6 ·
Replies
6
Views
6K
Proving C(AB) = C(A) with Orthogonal Complement and Matrix Multiplication
  • · Replies 3 ·
Replies
3
Views
2K
Intro to Linear Algebra - Nullspace of Rank 1 Matrix
  • · Replies 8 ·
Replies
8
Views
2K
Help with a Linear Algebra problem please
  • · Replies 3 ·
Replies
3
Views
1K
Comparing Basis Vectors in Linear Spaces: X and Y
  • · Replies 7 ·
Replies
7
Views
2K
Multiple Linear Regression (2 factors, 1 output)
  • · Replies 1 ·
Replies
1
Views
2K
Introduction to Linear Algebra: Solving Real-World Problems
  • · Replies 10 ·
Replies
10
Views
2K
Orthogonal Projection Problems?
  • · Replies 5 ·
Replies
5
Views
2K