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

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Anshika Goel 2017-9-14

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评论： Anshika Goel 2017-9-17

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.

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KSSV 2017-9-14

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 2017-9-14

编辑：Anshika Goel 2017-9-15

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.

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Answer 1

KSSV 2017-9-15

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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