How to solve for the coefficients of a polynomial equation?

I have a formula here:

T=A+BI+CI^2+DI^3

where T and I are known and varies, and A,B,C,D are my unknown constants...

With 4 unknowns, I would need to provide 4 equations.

How may I write these in matlab in order to solve for A,B,C and D?

Answer 1

[Azzi Abdelmalek]

I=1;T=3
%  A*y=b    your equation with y=[A;B;C;D]  are unknown variables 
A=[1 1 I^2 I^3     % your first equation T=A+BI+CI^2+DI^3
   1 3 4 5         % your second equation is A+3B+4C+5D=1
   4 5 1 2
   0 4 1 7]
b=[T;1;2;3]
y=A\b

[Sarah]

Hello,

shouldn't it be y=b/A?

[Walter Roberson]

No. A\b or b'/A'