# Thread: TI-89- Express Matrix as Product of Elementary Matrices

1. ## TI-89- Express Matrix as Product of Elementary Matrices

Does anyone know of a program or a way to express a given matrix as the sum of elementary matrices?

If not, maybe just a program that reduces a given matrix to the corresponding identity matrix?

Any help would be appreciated!

2. Hi

If your array is in A then the identity matrix may be found by:

A*A^-1

Please let me know if you need further assistance.

3. Originally Posted by RHandford
Hi

If your array is in A then the identity matrix may be found by:

A*A^-1

Please let me know if you need further assistance.
that's helpful, but i need the program to show the ERO's used at each step of reducing the given matrix A to the identity matrix. then i can use that information to write the corresponding elementary matrices. any ideas?

4. Hi

I have only just started learning matrix manipulation, so I am unsure what you are asking.
If you save a matrix, say A - you can get det(A) - the determinant, which is used to calculate A^-1.
If you can give me a small example of what you require, I may be able to assist further.

5. Originally Posted by RHandford
Hi

I have only just started learning matrix manipulation, so I am unsure what you are asking.
If you save a matrix, say A - you can get det(A) - the determinant, which is used to calculate A^-1.
If you can give me a small example of what you require, I may be able to assist further.
This is a pretty specific question so don't worry if you don't know how to do it. I thought I just might get lucky by asking in such a large forum Anyway, here is an example:

Express the given matrix A as the product of elementary matrices. (basically, we want to re-write a given matrix as the product of an arbitrary number of elementary matrices)

To do this, you can take the given matrix A, and reduce it to the corresponding identity matrix, taking note of the ERO's used along the way. Then, you use those exact ERO's on the identity matrix itself, and after each ERO performed you get one of the elementary matrices.

I need a program to reduce the given matrix to the identity matrix and show the ERO's along the way.