MATLAB Answers

how can curve fitting

11 views (last 30 days)
fereshte on 17 May 2014
Edited: fereshte on 29 Jun 2014
hi...i have some scatter points in x-y can curve fitting without using of cftool?i want do it by gussian fitt but in gussian code there are x and y.i domt know how obtain them!
% f = fit(x,y,'gauss8'); % plot(f,x,y); % coeff=fit(x,y,ft);
G is sample matrix with 106*47 in size and meanValue is mean of columns in matrix.result matrix is 1*47 that it is scatter points.
meanValue = mean(G)
thank you

  1 Comment

Image Analyst
Image Analyst on 17 May 2014
A screenshot of your data, or attaching your data file, would help us envision what you're talking about.

Sign in to comment.

Accepted Answer

Star Strider
Star Strider on 17 May 2014
Here’s my version of Gauss1 using fminsearch:
% % Single Gaussian Regression
% % Generate x- and y- data:
% x = linspace(0,10); % Generate x-data
% Normal distribution — b(1) = mean, b(2) = std
N = @(b,x) exp(-((x-b(1)).^2)./(2*b(2)^2)) ./ (b(2)*sqrt(2*pi));
% b = [5; 1];
% d1 = N(b,x); % Generate smooth y-data
% d2 = d1 + 0.05*(rand(size(d1))-.5); % Add noise
% % ————— Assign your variables to x and y here —————
x = your independent variable
y = your dependent variable
% % Use ‘fminsearch’ to do regression:
y = d2;
OLS = @(b) sum((N(b,x) - y).^2); % Ordinary Least Squares cost function
opts4 = optimset('MaxFunEvals',50000, 'MaxIter',10000);
B = fminsearch(OLS, rand(2,1))
Nfit = N(B,x); % Calculate estimated fit
The variables you need to have in your workspace are x and y (or assign them to x and y) to use this without modifying the code. The single ‘%’ commented lines are there for illustration. (Uncomment them if you want to see how it works. Remove them if you don’t need them.)


fereshte on 4 Jun 2014
thanks.this way is correct for soe images.but now i have a problem for one of them.i attached it in new post.please help me for values of b(1) and b(5) in this image.
Image Analyst
Image Analyst on 29 Jun 2014
Please put that "Answer" right here. No need to put a comment here and then say that Star has to look somewhere else down the page for it, especially since it's not really an "Answer" to your original post but a comment to Star.
fereshte on 29 Jun 2014
dear Star Strider
i use youre code for my dataset. but it dont work for all images. i change B line in this code respect to locs_Rwave for some images that dont get me true response.but its very difficult.can you help me to get the code that run perfectlly for all images with out any change in B line?

Sign in to comment.

More Answers (1)

Image Analyst
Image Analyst on 17 May 2014
How about polyfit. I've attached a demo.


Sign in to comment.

Sign in to answer this question.