Hi, could someone just start me off here?
I think it has something to do with $\displaystyle \partial E / \partial a_j$, j = 0, 1, 2, ..., n. But not sure exactly what to do.
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You want the mininum of:
$\displaystyle E=\sum_{i=0}^m w_i (f_i-\phi (x;a_0, .. , a_n))^2$
at the minimum:
$\displaystyle \frac{\partial E}{\partial a_j}=0$
or:
$\displaystyle \sum_{i=0}^m 2 x^j w_i(f_i-\phi(x;a_0, .. , a_n))=0$
rearranging:
$\displaystyle \sum_{i=0}^m x^j w_i\phi(x;a_0, .. , a_n))=\sum_{i=0}^m x^j w_i f_i$
Now rearrange the left hand side.
CB