How to solve 2n+2 nonlinear equations in MATLAB?

Here I want to solve these nonlinear equations. n is known and it is defined by function variable.

function[I]=solveequations[n]

where I0 I1 ... In are known, and A0 A1 ... An and x0 x1 ... xn are variables.

So how to calculate these 2n+2 nonlinear equations in MATLAB?

Thanks!

Answer 1

[Titus Edelhofer]

Hi Simon,

you might try to use fminsearch. For simplicity I assume A and x to count from 1 instead of 0. First write the objective function

function y = goal(X, I)
n = length(x) / 2;
A = X(1:n);
x = X(n+1:end);
f = zeros(n,1);
for i=1:n
  f(i) = sum(A .* x.^(i-1) - I(i));
end
y = sum(abs(y));

and then call fminsearch with

x = fminsearch(@(x) goal(x, I), x0);

where I is the vector of given I's and x0 some start vector like [A1, A2, ... An, x1, ..., xn]. As I said, probably you should rewrite first for A1...An instead of A0...An etc. to make life easier.

Titus