Similar Threads

1. fminsearch with three parameters

I'm trying to do an fminsearch on a function with three free variables and I get the following message :
??? Attempted to access p(3); index out of bounds because numel(p)=2.
Error in ==> @(p)lorfit(Table1,p(1),p(2),p(3))
Error in ==> fminsearch at 205
fv(:,1) = funfcn(x,varargin{:});
here's the code for my function lorfit :
function [ ansa ] = lorfit(x,G,x0,H)
ansa = 0;
for c = 1:length(x)
ansa = ansa + (x(c,2) - (H/(2*((x(c,1)-x0)^2+(G/2)^2))))^2;
end
ansa = sqrt(ansa);
end
Can someone tell me what I'm doing wrong?

2. "special" to fit a three-parameter function - MATLAB

3. weibull three parameters

Hi,
I would like to adjust a series of extremal data to the weibull of three parameters function of which its CDF reads:
F(x) = 1-exp(-(x-gamma/beta)^alpha)
how can I obtain the values of these parameters for my data?
I was looking for this function in Matlab, but I think it is not supported by the statistics toolbox (it only appears weibull of two parameters)
Any help is appreciated. Thanks in advance!

4. three-parameter distribution - MATLAB

5. Fitting a model to three parameters with data point repetitions

Hello,
I have three parameters, abbreviated by c, m, p. The dataset i have has four columns:
index
c
m
p
Index is just a uniquely identifier for each row. There are 3167 rows in the data.
I intuitively can say that the parameters c, m, p are have a correlation. However, what I can definitely say is that p>m for each row.
What I need to do is to fit a model to these parameters so that I can correlate them in one equation. Instead of fitting a model for three parameters, I tried to fit a model to C(3,2)=3 pairs of these paramaters: (c,m), (c,p), (m,p). So I drew their scatterplots and started fitting, with various methods.
The challenge here is that for each of these three scatterplots, there are multiple y values for one x value. So if we are to fit a function to any of the scatterplots, f(x) will give a single y value, whereas the data has multiple y values.
I used splines, smoothing, regression... and such. The fitting is clearly not good. Moreover, I cannot get the equation of the model that I fit using these methods, I just plot the fitting function (which is actually, just visually, not a good fit) and don't even know the the form of the function itself at all.
What else can I do to find a correlation among these three parameters? Can I have a good fit and can I know the function of the fit at the same time? Is there a better approach to fit a model to three parameters, where some of the data are repeated?
Thanks.

6. Fminsearch over 20 parameters - MATLAB

7. fminsearch mle parameters

hello,
I am trying to use fminsearch to solve for the paramter phee. Whenever
I type:
phiHat = fminsearch(exact(z,x),z,x);
I get the error message:
??? Error using ==> fcnchk at 105
FUN must be a function, a valid string expression,
or an inline function object.
Error in ==> fminsearch at 178
funfcn = fcnchk(funfcn,length(varargin));
my function is defined as:
function result = exact( h,q)
% Estimation
% =============
x = q(:); % should be column vectors !
z =h(:);
phee = (inv(x'*x))*(x'*z);
N = length(x);
sig2 = (z-phee*x)'*(z-phee*x)/N;
w = (N/2/log(2*pi))+(N/2)*log(sig2)+((z-phee*x)'*(z-phee*x))/
2*sig2;
result = struct( 'phee',phee);
end
I have no idea what I am doing wrong, any help would be welcome!
-Nora

8. Breaking out of fminsearch given a parameter - MATLAB