MATLAB, Problem with lsqcurvefit

1. Problems with lsqcurvefit - MATLAB

2. problem in lsqcurvefit

Hi

I have a dataset for x,y which I need to fit with following equation(y=f(x,y)).
y=(4.1/lp)*((1./(4*(1-(x/L-(y/K0))).^2))+x/L-(y/K0)-0.25);
where lp, L and K0 are the parameters used for optimization.

I am using lsqcurvefit to ooptimize the parameters and here is my .m file.

l=load('...');
x=l(:,1);
y=l(:,2);
data=[x y];
zdata=y;
c0=[0.7 1 50000];
F=(4.1/c0(1))*((1./(4*(1-(x/c0(2))+(y/c0(3))).^2))+(x/c0(2))-(y/c0(3))-0.25);
[c, resnorm]=lsqcurvefit(@myfun,c0,data,zdata)
end

However, when I run this, it generates following error:

?? Maximum recursion limit of 500 reached. Use set(0,'RecursionLimit',N)
to change the limit.  Be aware that exceeding your available stack space can
crash MATLAB and/or your computer.

Error in ==> optimget


Caused by:
    Failure in initial user-supplied objective function evaluation. LSQCURVEFIT cannot continue.

I changed the recursion limit to 5000 and run. Unfortunately this crashes the matlab.

Looking for help.

Thank you

rakshit

3. problems with lsqcurvefit and quad (loop) - MATLAB

4. Problem with lsqcurvefit Display option

I'm running Matlab 6.5 (Student Version) and the Optimization Toolbox 
version 2.2

When I run lsqcurvefit on my data, with no options specified, I get the 
message:

Optimization terminated successfully:
  Relative function value changing by less than OPTIONS.TolFun

When I use the "optimset" command to set the Display option:

   options = optimset('Display','notify');
   x = lsqcurvefit(f,x0,x1data,ydata,lb,ub,options);

I get the same "Optimization terminated successfully" message.

I thought that setting "Display" to "notify" meant that I'd only get 
output if the function failed to converge, and "Optimization terminated 
successfully" would seem to indicate that the function *did* converge.

Am I misunderstanding the meaning of "Optimization terminated successfully"?

Am I misunderstanding what "Display = notify" does?

Is this a bug?

FWIW, "Display = final", "Display = iter" and "Display = off" appear to 
work as expected.   Note that "Display = final" and "Display = notify" 
give the same result.

Bob Pownall

5. curve fitting problem with lsqcurvefit - MATLAB

6. lsqcurvefit cannot seem to solve allometric problem?

I have a set of (x,y) that I want to fit using the allometric relation:

y = a*(y-b)^c

so I would need to estimate 3 variables (a,b,c). However, after modifying numerous online examples and doing my own, I always get the QR error about complex values (even when I set the upper and lower bounds to real numbers).
For example:

xdata=[0.006828287172237330
0.790682195827279000
0.003735589633394300
0.588505280987413000
0.049935384458074200
0.249101128117032000
];

ydata=[0.000422158958434916
0.476084662925104000
-0.003271705711918840
0.335717811245073000
0.006198209732454980
0.062046706155897800
];

predicted = @(a,x) a(1)*(x - a(2)).^a(3);
a0=[2;2;2];
[ahat,resnorm]=lsqcurvefit(predicted,a0,xdata,ydata);

------> Results in:
"??? Error using ==> qr
Complex sparse QR is not yet available. ..."

Any ideas? Did I use this incorrectly?
Thanks in adavance!
Eric

7. lsqcurvefit boundary problem - MATLAB

8. lsqcurvefit problem

i'm trying to fit two curves using the lsqcurvefit.
to do that i need to define a function

predicted=@(x,Xdata_3500) 
x(1)*x(2)*(x(3)+1)*(((Xdata_3500-(-2.5))./x(4)).^(x(3))).*exp(-x(2)*(((Xdata_3500-(-2.5))./x(4)).^(x(3)+1)))+(1-x(1))*x(5)*(x(6)+1)*(((Xdata_3500-(-2.5))./x(7)).^(x(6))).*exp(-x(5)*(((Xdata_3500-(-2.5))./x(7)).^(x(6)+1))) ;
x0=[0.5;5;2;10;6;1;80];
[ahat,resnorm,residual,exitflag,output,lambda,jacobian]=...
lsqcurvefit(predicted,x0,Xdata_3500,Ydata_3500);   

i've noticed that each time i change x0 values and run lsqcurvefit again, i'm obtaining new parameters for ahat.

although the 2 curves are well coherent, i have constraints concerning the parameters, and i need them to respect certain intervalls.

any advice?