You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: eig_sshopm.m
    path of file: ./repos/tensor_toolbox
    
    the code of the file until where you have to start completion: function [lambda,x,flag,its,x0] = eig_sshopm(A,varargin)
%EIG_SSHOPM Shifted power method fo
    
function alpha = adapt_shift(A,x,tau,concave)

m = ndims(A);
Y = ttsv(A,x,-2);
e = eig(Y);

if concave
    if max(e) <= -tau/(m^2-m)
        alpha = 0;
    else
        alpha = -(tau/m) - ((m-1)*max(e));
    end