# [SOLVED] Elementary Matrix

• Jan 27th 2010, 10:41 AM
Noxide
[SOLVED] Elementary Matrix
Just double checking...

Row 3 multiplied by (-1)
is represented by an identity matrix with I33 = -1, correct?

and it's inverse is just the identity matrix?
• Jan 27th 2010, 10:48 AM
Moo
Hello,
Quote:

Originally Posted by Noxide
Just double checking...

Row 3 multiplied by (-1)
is represented by an identity matrix with I33 = -1, correct?

Yes

Quote:

and it's inverse is just the identity matrix?
No, its inverse is itself. Just check the multiplication :)
• Jan 27th 2010, 10:58 AM
Noxide
Thanks, I though that was the case.

I know that P32's inverse is P32, but should I even bother writing the -1 superscript?
• Jan 28th 2010, 12:26 AM
HallsofIvy
Quote:

Originally Posted by Noxide
Thanks, I though that was the case.

I know that P32's inverse is P32, but should I even bother writing the -1 superscript?

You realize, don't you, that no one has any idea what you mean by "P32"?
• Jan 28th 2010, 08:45 AM
Noxide
Oh, I thought it was a convention that Pxy was a permutation matrix.