I need to apply ?sytrf to a Matrix (A) then add a diagonal Matrix (λ I) to the output of the sytrf and after that use ?sytrs to solve a system of linear equations. However I can’t understand how output sytrf is written and what is the right way to add the diagonal matrix to get the Bunch-Kaufman factorization of the sum sytrf ( A + λ I) of the matrices. Adding the diagonal matrix before the using the function sytrf is not possible in the algorithm that we are using.
sytrf ( A + λ I) = sytrf ( A ) + C
Can't find the right way to add C to the sytrf ( A ).
I would be very grateful if someone can help me with this.
Thank you again,