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curve fitting for different data

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Ahmed Abdalazeez 2019-10-9

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关闭： MATLAB Answer Bot 2021-8-20

num.fig
num.png

Hello,

I have a data from different factors, I need to make a fitting curve as an estimation function for them.

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Star Strider 2019-10-9

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Do you have a mathematical description of the process that created these data? Any number of functions could fit them, however estimating the parameters of the process that created them is the only one that would make any sense.

Ahmed Abdalazeez 2019-10-10

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Hi,

Thank you for your response!

I normalized these data by taking the parameter-constant- (L/\lambda)^1/4, so then I get thier distribution as it shown in this figure. Now I want indepentent function can estimate y according to x.

Star Strider 2019-10-10

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My pleasure.

It would be extremely helpful to know exactly what you are plotting, and the mathematical model of the process that produced those data, as well as the normalisation constants and other information.

We still do not have any of that information.

Ahmed Abdalazeez 2019-10-10

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Thanks a lot!

Well, Y- axces is the runup values times (Lnegth of beach slope/Wavelength = 20/70) vs steepness of incident wave. The data isa results of NLSW equations. Both xand y nondimensional. These different colors are different intial periods.

Hope these information help you to get helping from you :)))

Thanks in advance!!

Star Strider 2019-10-10

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What parameters would you want from a curve fit to your data?

Are there any literature references that you can post (preferably as .pdf files) that could explain this in more detail, for those of us who (like me) have very little understanding of littoral dynamics?

Have others estimated these parameters? If so, what models did they use?

Ahmed Abdalazeez 2019-10-10

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Actually, I am just looking for the best power curve fitting of (s/s0), I found:

fit= ((70/20).^(1/8)*(((s/s0).^(1/4)))); but I am not sure if it is the best fitting.

Star Strider 2019-10-10

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在 MATLAB Online 中打开

What parts of this equation:

fit = ((70/20).^(1/8)*(((s/s0).^(1/4))));

represent parameters you want to fit? The exponents? s0?

Ahmed Abdalazeez 2019-10-10

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I need the fitting of (s/s0) in x axces

Star Strider 2019-10-10

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As I interpret it, ‘s’ are data, so ‘s0’ would be the parameter you want to estimate. Is this correct?

Before I attempt to extract your data from the figure you posted, what are they? If you already assumed a value for ‘s0’, then there is nothing to estimate.

I am still not certain what you are doing, or what your data are.

Ahmed Abdalazeez 2019-10-10

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No, (s/s0) is x-axes, so you can call them S or anything. i want interpret (Rmax/Ro) with regarding S.

Rmax/R0 = b * S^x.

this what I need, hope now is clear.

Thanks a lot

Star Strider 2019-10-10

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O.K. That much is now clear.

I still need to know what your data are. I assume in ‘num.fig’ that ‘s/s0’ is ‘x’. Is that correct? What is ‘y’? I am still not certain what the plot represents, or what the data are that are plotted.

Ahmed Abdalazeez 2019-10-10

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yes, in .fig

x-axes: s/s0

y=axes: Rmax/R0*(L/lambda)^1/4.

AND, (L/lambda)^1/4 is constant

Star Strider 2019-10-10

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How am I supposed to estimate Rmax/R0, or Rmax or R0 if that calculation has already been done?

What is the value of (L/lambda)^1/4?

Ahmed Abdalazeez 2019-10-10

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How am I supposed to estimate Rmax/R0?

OK, what I need, I just need a perfect fitting with these data R VS S

Regarding to the value of (L/lambda)^1/4 = (20/70)^1/4.

Star Strider 2019-10-10

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I am not getting the information I need.

Ahmed Abdalazeez 2019-10-10

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Suppose, it as experimental data distributed as in the figure above. What I have here the value of Rmax/R0 is calculated directly. So, from these data i need the best fit as power function for example Rmax/R0 = a*(s/s0)^x.

I tried the formula above but I not sure if is the best fitting or not.

Ahmed Abdalazeez 2019-10-11