Not understanding symbols

[frctl]

While looking at my exercises:

Determine whether the given matrix expression is defined. For those that are defined, give the size of the resulting matrix.
A - 3E^T

Use the following matrices to compute the indicated expression if it is defined.
tr(D)

I do not know what the symbol ^T and tr() mean.

 

[tkhunny]

The both mean "Transpose". If it's square, grab the matrix by the main diagonal and flip the upper-right corner around to become the lower-left corner. Note: There ARE more technical descriptions. Maybe, make all the columns rows and at the same time make all the rows columns.

 

[frctl]

Ah thank you for explaining to me.

 

[Steven G]

tr() is only defined for square matrices. Let D be one such matrice. Then tr(D) is the sum of the elements on the main diagonal.

 

[tkhunny]

tr() is only defined for square matrices. Let D be one such matrice. Then tr(D) is the sum of the elements on the main diagonal.

Oh, right. I do appreciate ambiguous notation.

 

[Dr.Peterson]

I missed that myself: tr means "trace": http://mathworld.wolfram.com/MatrixTrace.html

Does your textbook define these terms and symbols?

 

[frctl]

If Matrix D is
1 5 2
-1 0 1
3 2 4

What is tr(D)

 

[Deleted member 4993]

If Matrix D is
1 5 2
-1 0 1
3 2 4

What is tr(D)

How does your textbook define "tr"?

 

[Dr.Peterson]

If Matrix D is
1 5 2
-1 0 1
3 2 4

What is tr(D)

You were told in post #4, and in the link I provided in post #6.

The answer is, tr(D) = 1+0+4 = 5. Do you see that? Doesn't your book give you both a definition and an example?

 

[Otis]

Are you finished with this exercise, frctl?