Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: √ ∞ ≠ ≤ ≥ ≈ ⇒ ∈ Δ θ ∴ ∑ ∫ π -

Login

Username

Password

Not registered yet?

#1 2009-12-11 01:39:22

integer
Full Member

Offline

Is there a name for the other diagonal of a matrix?

I'm looking for a definition or name for the diagonal from the lower left to the uper right of a matrix,

Example: 2x2 matrix



The diagonal from the upper left to the lower right is identified as "main diagonal".
   
The trace(A) is the sum of the elements along the main diagonal.

 
The question:  Is there a name for the diagonal from the Lower-left to the upper-right?
 


Or do you have a reference/resource that might have a name for this diagonal?

 

#2 2009-12-11 02:37:17

mathsyperson
Moderator

Offline

Re: Is there a name for the other diagonal of a matrix?

I've seen that referred to as the antidiagonal. Not sure how common the usage of that is though.


Why did the vector cross the road?
It wanted to be normal.
 

#3 2009-12-19 11:16:18

integer
Full Member

Offline

Re: Is there a name for the other diagonal of a matrix?

mathsyperson wrote:

I've seen that referred to as the antidiagonal. Not sure how common the usage of that is though.

Thank you.

Searching for "antidiagonal" gave other terms also used:
  subsidiary diagonal
  secondary diagonal.
 
Subsidiary diagonal can be confushed with superdiagonal/subdiagonal when refering to tridiagonal matrices.
 
The "main diagonal" is the "primary diagonal" and the "antidiagonal is the "secondary diagonal".
I like that.
 
Again, Thank you.

 

Board footer

Powered by FluxBB