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Author Comment/Response
Bill Simpson
10/18/12 3:47pm

In Response To 'Re: Re: Plotting non-linear values and solving'
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I originally looked at Fit and FindFit and couldn't see a way to apply these.

I go to
http://reference.wolfram.com/mathematica/ref/FindFit.html
and click on Scope and then Multivariate data.

That example certainly isn't the simplicity I would want when I'm confused and trying to see a brilliantly clear example, but I type it all back in and look at each of the intermediate values and try to reverse guess how to apply that.

I think for your problem I want to do this

In[1]:= data = {{0.0000079, 0.244},{0.0000119, 0.295},
{0.0000158, 0.428},{0.0000198,0.488},
{0.0000237, 0.703}, {0.0000277,0.711},
{0.0000316, 0.859}, {0.0000356,0.878},
{0.0000395, 0.926}, {0.0000435,0.915},
{0.0000474, 0.991}, {0.0000593, 1.04},
{0.0000632, 1.02}};
y = ((1 + (K(0.000011501)) + (K(x)/(2s))) - ((1 + (K(0.000011501)) + (K(x)/(2s)))^2 - (2K^2(0.000011501(x)))/s))^.5/((2K(0.000011501)));
FindFit[data, y, {{K, 2*10^6}, {s, 1}}, x]

and that gives me this

FindFit::nrlnum: The function value {-0.244+0.350I, <<9>>, <<3>>} is not a list of real numbers with dimensions {13} {K, s} = {2*^6, 1.}

which again is showing that for some, maybe lots, of values of K your square roots are resulting in complex values and most of the functions looking for real results give up the moment they see a complex value.

All this is part of the reason I fell back on using Norm and minimize to look for the best approximation I could find.

Is any of this getting you closer to your solution?

Is there some way to find a domain for K and s that give real results? Perhaps that would help.

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Subject (listing for 'Plotting non-linear values and solving')
Author Date Posted
Plotting non-linear values and solving sk597653 10/17/12 3:05pm
Re: Plotting non-linear values and solving Bill Simpson 10/17/12 11:22pm
Re: Re: Plotting non-linear values and solving sk597653 10/18/12 12:57pm
Re: Re: Re: Plotting non-linear values and solv... Bill Simpson 10/18/12 3:47pm
Re: Re: Re: Re: Plotting non-linear values and ... sk597653 10/20/12 4:47pm
Re: Re: Re: Re: Re: Plotting non-linear values ... Bill Simpson 10/22/12 02:06am
Re: Re: Re: Re: Re: Re: Plotting non-linear val... sk597653 10/23/12 10:40am
Re: Re: Re: Re: Re: Re: Re: Plotting non-linear... Bill Simpson 10/23/12 11:57pm
Re: Re: Re: Re: Re: Re: Re: Re: Plotting non-li... sk597653 10/26/12 4:22pm
Re: Re: Re: Re: Re: Re: Re: Re: Re: Plotting no... Bill Simpson 10/26/12 9:53pm
Re: Re: Re: Re: Re: Re: Plotting non-linear val... sk597653 10/23/12 11:09am
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