Curve smoothing using Matlab

I have got an experimental curve which is a bit wavy (curve has a lot of noise and hence is wavy).

I want to smoothn the curve using Matlab.

Can anyone advise the best tool in Matlab for this?

I wanted to attach the plot of curve which needs to be smoothened but couldn't find a way to attach it here.

shalini

Answer 1

[Jonathan Sullivan]

help filter
doc filter

[Shalini]

Do you mean:

yy = smooth(y)

where; yy is the smoothed vector? And, y is the dependent variable (of the curve) that needs to be given?

Answer 2

[Richard Willey]

I have a function called FitIt on the file exchange that might prove useful.

FitIt combines

Local regression (to smooth your data set) Cross validation (to estimate an optimal spanning parameter) Bootstrap (to generate confidence intervals)

FitIt has dependencies on both Curve Fitting Toolbox and Statistics Toolbox.

[Shalini]

Sorry Richard, I was sick for 2 days..how can I access your function FitIt through fiel exchange?

Please help

[Richard Willey]

Hi Shalini

You can download the function from

http://www.mathworks.com/matlabcentral/fileexchange/31562-data-driven-fitting-with-matlab

Please note: Under the hood, this function uses the "Smmoth" function that Sean is recommending. The major difference is that I added some code that automatically computes an optimal spanning parameter for the smooth function and also gives you the option of computing confidence intervals.

There is a recorded webinar available on this topic at

http://www.mathworks.com/company/events/webinars/wbnr56627.html?id=56627&p1=961661709&p2=961661727

[Taymaz Tek]

Hi everybody,

I had been trying to use your function, fitit, in my own problem but it didn't work well. In the case of your demo, it is quite ok but when I try to run it with my signal, there is an error:

??? Error using ==> horzcat

CAT arguments dimensions are not consistent.

Error in ==> fitit at 21

sse(j) = sum(crossval(f,[X,Y],'partition',cp));

can you please let me know where this can be driven?

[Taymaz Tek]

Thanks in adavnce

Answer 3

[Sean de Wolski]

How about smooth() :)

doc smooth

[Shalini]

I'm new to matlab...How to use this smooth?Why do you say doc smooth? Is there a document?

[Sean de Wolski]

If you run:

doc smooth

at the command line it will tell you all about the SMOOTH function, (well as long as you have a somewhat recent version of MATLAB with the Curve Fitting Toolbox)

[Samuel Suakye]

figure clear; clc; delta=[0.0259, 0.0518, 0.0776, 0.1035, 0.1293]*10; %delta=0.01:0.09:0.5; delta1=0.01:0.1:0.5; hbar=6.5821220*10e-16; k=8.617385*10e-5; T=300; d=[100 150 200]*10e-10; m = 9.1093897*10e-31; v = 2.8*10e8; c = 3.0*10e8; wp = 10e12; w = 0.7071; gamma = (1-((v^2)/(c^2)))^-0.5; delta2= delta1./(k*T); %% figure hold on for i = 1:length(d) wo=(wp^2*m*d(i)^2*delta1.*besseli(1,delta2))./(hbar^2*besseli(0,delta2)).^(0.5); delta3=delta./(k*T); therta = asind(1-(w.^2./wo.^2)).^0.5; wb = gamma.*wo.*cosd(therta); %wb^2=2 rho=(hbar^2.*2.*besseli(0,delta3))./(wp^2*m*d(i)^2*k*T.*delta3.*besseli(1,delta3)); plot(delta3,rho,'LineWidth',1.5) end %% xlabel('\Delta^*') ylabel('E_b/E_s') hold on grid on All comments are not working for my codes above