Hi
I would like to implement ssteqr and ssytrd in the linalg backend representing implicit ql algorithm using MRRR and its symmetric matrix tri-diagonalization respectively. However, I cannot locate where to include this modifications.

subroutine ssteqr ( character COMPZ,
integer N,
real, dimension( * ) D,
real, dimension( * ) E,
real, dimension( ldz, * ) Z,
integer LDZ,
real, dimension( * ) WORK,
integer INFO
)

subroutine ssytrd ( character UPLO,
integer N,
real, dimension( lda, * ) A,
integer LDA,
real, dimension( * ) D,
real, dimension( * ) E,
real, dimension( * ) TAU,
real, dimension( * ) WORK,
integer LWORK,
integer INFO
)

Thanks a lot sir @ptrblck . Would I need to rebuild the torch package to implement because I plan to implement the modification on a Jetson Nano device.

Yes, if you manipulate these files you would need to rebuild PyTorch from source.
Alternatively, you could try to write a custom extension as described here.