Curve fit for multiple variables

I have an equation of form y=a*(x1^b)*(x2^c)*(x3^d)*(x4^e)

where x1, x2, x3, x4 are variables and y is output. I have all these values experimentally.

I need to fit this equation to calculate optimum values of a, b, c, d and e.

Please provide a suitable matlab code.

Answer 1

[Andrei Bobrov]

x = [x1(:) x2(:) x3(:) x4(:)];
abcde = [ones(numel(y),1),log(x)]\log(y);
abcde(1) = exp(abcde(1));

your function

yourfun = @(x,a)a(1)*prod(bsxfun(@power,x,reshape(a(2:end),1,[])),2);

Please read about use '\'