## lapack for eigen values

## lapack for eigen values

(OP)

hi, i have problem of the form AX=lamda.BX and wish to get the eigen values for this.. A and B are 2 symmetric square matrices. i am trying to use lapack routines in fortran95 on win64 pc. the matrices A and B are prepared in the program from certain calculations..as per the routine, A and B are to be in Upper or lower triangular form - how do i achieve my existing matrices in this format.

thanks,

rkr

thanks,

rkr

## RE: lapack for eigen values

If you are interested in the Python/Scipy approach, you might like a look at my spreadsheet at:

xlScipy with xlwings

Doug Jenkins

Interactive Design Services

http://newtonexcelbach.wordpress.com/

## RE: lapack for eigen values

## RE: lapack for eigen values

Having recently spent a couple of weeks trying to get F2PY (Fortran to Python) running, after changing from Python 2 to 3, I can certainly empathise with the reluctance to use another language, nonetheless I think it's worth you having a look at the Scipy documentation, as their linear algebra routines seem to be simply a front end to LAPACK, and the manual does have a fair bit of background information on matrix formats. The link below may (or may not) be of some use:

http://docs.scipy.org/doc/scipy/reference/tutorial...

Regarding the specific question, the comments for dsgesv that you provided refer to:

A (input/output) DOUBLE PRECISION array,dimension (LDA,N)

* On entry, the N-by-N coefficient matrix A.

and

B (input) DOUBLE PRECISION array, dimension (LDB,NRHS)

* The N-by-NRHS right hand side matrix B.

So it doesn't seem to say anything about A and B being in upper triangular form, or am I missing something?

Doug Jenkins

Interactive Design Services

http://newtonexcelbach.wordpress.com/