Extracting the coefficient of a polynomials matrix

I want to extract the coefficients of a polynomial matrix P(x) with sym x, which can be decomposed into P0 + P1x + P2x^2 ....

A example can be sym x

P = [1 + x x^2; x^3 x^4];

I understand that one might apply the function coeffi to each entry of P(x) to handle this problem. However, I wonder if there are more efficient ways to achieve this task.

Answer 1

[Kwin]

You could differentiate and evaluate P at x=0, so

P0 = subs(P, x, 0);
P1 = subs(diff(P), x, 0);
P2 = subs(diff(P,2)/2, x, 0);
P3 = subs(diff(P,3)/factorial(3), x, 0);
P4 = subs(diff(P,4)/factorial(4), x, 0);

would give you your matrices.

In general the nth polynomial matrix of P can be found with,

Pn = subs(diff(P,n)/factorial(n), x, 0);

[Qian Feng]

Thanks a lot, this is a very smart approach.