Construct L and U from dgbtrf
Posted: Mon Oct 27, 2008 7:14 amHi,
I am using the LAPACK function dgbtrf to factorize a band matrix. I know it is usual to just hand over the result matrix to a solver (dgbtrs), but I need to obtain two separate matrices L and U. Unfortunately I don't understand in which way those matrices are stored in the output matrix of dgbtrf. U is quite obvious, but how can I derive L from those strange factors m(i,j)?
Thanks!
I am using the LAPACK function dgbtrf to factorize a band matrix. I know it is usual to just hand over the result matrix to a solver (dgbtrs), but I need to obtain two separate matrices L and U. Unfortunately I don't understand in which way those matrices are stored in the output matrix of dgbtrf. U is quite obvious, but how can I derive L from those strange factors m(i,j)?
Thanks!