I have a third degree equation, with variable a matrix of 256*256. How can I solve it in MATLAB?

I have tried to solve it using fsolve; but it is solving only upto 64*64 matrix. The equation is ax^3+bx^2+cx+d=0; where a,b,c and d are constant matrix of 256*256 size. And x is variable of same size 256*256.

[KSSV]

Then you can split your matrix into sub blocks of size 64*64 and solve it..:)

By the way what equation it is? You have to show us the code.

[Anshika Goel]

ax^3+bx^2+cx+d=0; where a,b,c and d are constant matrix of 256*256 size. And x is variable of same size 256*256.

By splitting the matrix into sub blocks, the program is taking much time to execute.

Answer 1

[KSSV]

Let A,B,C,D be your respective coefficients (Ax^3+Bx^2+Cx+D=0) of size 256*256..

R = zeros(n,n,3) ;  % roots initialized 
for i = 1:n
    for j = 1:n
        p = [A(i,j) B(i,j) C(i,j) D(i,j)] ;
        r = roots(p) ;
        R(i,j,:) = r ;
    end
end

[Anshika Goel]

Thank you Sir. It is giving much faster results in comparison to fsolve.