How can I triangular a matrix

I have a n*n matrix. I want to change it to a triangular matrix. please help me.

[James Tursa]

Is your homework assignment to code up your own Gauss elimination scheme to get the upper triangular matrix?

Answer 1

[Matt J]

There are commands TRIU and TRIL to convert a matrix to upper and lower triangular, if that's what you mean.

[Amir Ehsani]

Thanks. But actually I want transform a n*n matrix to upper triangular matrix to calculate the determinant. I have a big problem with n*n matrix determinant.n>=16

[Matt J]

1. If you want to transform the matrix to upper triangular, then why is TRIU inappropriate?
2. How will this transformation help in computing the determinant? Such a transformation would change the determinant.
3. Why is n>=16 a big deal? MATLAB will do determinants pretty easily for n in the thousands

>> A=rand(3000); tic; det(A); toc
Elapsed time is 0.591271 seconds.