MATLAB: What does roots/ eig do exactly

Question

I want to write a programm on Matlab, without using implemented functions. This programm should be similiar to the Matlab function roots. But I am not sure what roots does, is there any possibility to read something like a pseudo-code of roots or eig? Or is it possible to find .m file that fullfills this conditions?

Is roots simply using the QR decomposition with shifts ?

Answer 1

>>edit roots