clc
clear


N = 100; 
A = randn(N); 
M = randn(N); 
b = randn(N, 1);

tol = 10^(-7); 
max_it = 10*N; 
n_step = 4; 
n_max = 10*n_step;

x = zeros(N, 1); 
r = b-A*x;
Q = [r, sign(randn(N, n_max - 1))];
n = find_n(A, b, Q, M, n_step, n_max);
[x, err, iter, flag] = mlbicgstab(A, x, b, Q(:, 1:n), M, max_it, tol);