Re: fitting, step

From: Michael Nowak <mnowak_at_email.domain.hidden>
Date: Thu, 8 Jul 2010 06:37:03 -0400
On Jul 8, 2010, at 6:18 AM, John Houck wrote:

> In retrospect, it seems rather obvious that 1% is too large for
> the default step size because line centers in grating
> observations are measured much more accurately than that.
>> Just curious, since in using ISIS here in he summer school for
>> high res spectra, I've noticed that mpfit *can* be a little
>> fussy on narrow lines, unless one runs conf_loops and forces
>> fits to find new, lower chi^2, and/or uses subplex.  Either
>> makes Monte Carlo simulations of line significances a little
>> slower.
> I hope this change will solve that problem.

Aha!  Yes, makes excellent sense to me.  I think I was trying step sizes *slightly* larger than Maurice, but still quite small, precisely because 1% is so obviously off a well-detected line.  A lot of my step sizes were on the order of 0.3%.

So, thanks Maurice for bringing this to our attention!

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Received on Thu Jul 08 2010 - 06:37:07 EDT

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