User talk:Petergans/b/sandbox

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[edit] Linear and nonlinear

  • Should perhaps underline that linearity/nonlinearity is with respect to the fitting parameters, rather than the underlying variables.
In particular it should perhaps be emphasised that a function
y = \Sigma \, a_i \phi_i (\mathbf{x})
although nonlinear in x, is linear in the weights ai, so can still be fitted by Linear least squares.
On the other hand NLLS will be required when the function looks like
y = \psi(\mathbf{a}, \mathbf{x})
-- Jheald (talk) 23:04, 30 January 2008 (UTC)

[edit] Marquandt parameter

  • Should mention Moré approach for setting it, used in the best production codes.
  • Perhaps mention connection to trust-region, with λ coming out as a Lagrange multiplier. Jheald (talk) 23:04, 30 January 2008 (UTC)

[edit] Non-linear or nonlinear?

Should there be a dash in the article name or not? I sort of like it with the dash, the way Petergans wrote it, but I guess both are fine. Oleg Alexandrov (talk) 04:14, 1 February 2008 (UTC)

I prefer without the hyphen-dash, following Nonlinear system. Is there some sort of guideline for this in the math style guide? CRGreathouse (t | c) 20:21, 1 February 2008 (UTC)