Simple fitting problem
in [Matlab]
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From: Aino on 10 Jul 2010 23:05 Hi All, I am having trouble with fitting. Here's a simple version of what I am trying: clear all x=[1:100]; y=0.1*sin(x)+2; s = fitoptions('Method','LinearLeastSquares','Lower',[0 0]); ffun = fittype('a*sin(x)+b','coefficients',{'a','b'},'independent','x','options',s); f=fit(x',y',ffun) And here's what I get: ??? No appropriate method, property, or field startpoint for class curvefit.llsqoptions. Error in ==> fit at 325 start = options.startpoint; Matlab helps tells me that when I have "LinearLeastSquares" as a method I have the option to set a lower limit to the fit. This is driving me crazy.. I need to get the lower limit to the fit since the function I am really using in my code -log(a^x+b^x)/log(2) calculates complex values when x is a negative integer, and a and b are negative and my code stops there. Thank You for your help. -Aino
From: us on 11 Jul 2010 06:05 "Aino" <aino.tietavainen(a)removeThis.helsinki.fi> wrote in message <i1bcd4$o8i$1(a)fred.mathworks.com>... > Hi All, > > I am having trouble with fitting. Here's a simple version of what I am trying: > > clear all > x=[1:100]; > y=0.1*sin(x)+2; > s = fitoptions('Method','LinearLeastSquares','Lower',[0 0]); > ffun = fittype('a*sin(x)+b','coefficients',{'a','b'},'independent','x','options',s); > f=fit(x',y',ffun) > > And here's what I get: > ??? No appropriate method, property, or field startpoint for class > curvefit.llsqoptions. > > Error in ==> fit at 325 > start = options.startpoint; > > Matlab helps tells me that when I have "LinearLeastSquares" as a method I have the option to set a lower limit to the fit. This is driving me crazy.. I need to get the lower limit to the fit since the function I am really using in my code -log(a^x+b^x)/log(2) calculates complex values when x is a negative integer, and a and b are negative and my code stops there. > > Thank You for your help. > > -Aino which ver of ML and the curve fitting tbx do you have(?)... us
From: Aino on 11 Jul 2010 06:51 "us " <us(a)neurol.unizh.ch> wrote in message <i1c50h$l32$1(a)fred.mathworks.com>... > "Aino" <aino.tietavainen(a)removeThis.helsinki.fi> wrote in message <i1bcd4$o8i$1(a)fred.mathworks.com>... > > Hi All, > > > > I am having trouble with fitting. Here's a simple version of what I am trying: > > > > clear all > > x=[1:100]; > > y=0.1*sin(x)+2; > > s = fitoptions('Method','LinearLeastSquares','Lower',[0 0]); > > ffun = fittype('a*sin(x)+b','coefficients',{'a','b'},'independent','x','options',s); > > f=fit(x',y',ffun) > > > > And here's what I get: > > ??? No appropriate method, property, or field startpoint for class > > curvefit.llsqoptions. > > > > Error in ==> fit at 325 > > start = options.startpoint; > > > > Matlab helps tells me that when I have "LinearLeastSquares" as a method I have the option to set a lower limit to the fit. This is driving me crazy.. I need to get the lower limit to the fit since the function I am really using in my code -log(a^x+b^x)/log(2) calculates complex values when x is a negative integer, and a and b are negative and my code stops there. > > > > Thank You for your help. > > > > -Aino > > which ver of ML and the curve fitting tbx do you have(?)... > > us I just switched form 2009b to 2010a, my toolbox seems to be v2.2. Does this work with your Matlab? -Aino
From: Aino on 11 Jul 2010 09:13 "us " <us(a)neurol.unizh.ch> wrote in message <i1c50h$l32$1(a)fred.mathworks.com>... > "Aino" <aino.tietavainen(a)removeThis.helsinki.fi> wrote in message <i1bcd4$o8i$1(a)fred.mathworks.com>... > > Hi All, > > > > I am having trouble with fitting. Here's a simple version of what I am trying: > > > > clear all > > x=[1:100]; > > y=0.1*sin(x)+2; > > s = fitoptions('Method','LinearLeastSquares','Lower',[0 0]); > > ffun = fittype('a*sin(x)+b','coefficients',{'a','b'},'independent','x','options',s); > > f=fit(x',y',ffun) > > > > And here's what I get: > > ??? No appropriate method, property, or field startpoint for class > > curvefit.llsqoptions. > > > > Error in ==> fit at 325 > > start = options.startpoint; > > > > Matlab helps tells me that when I have "LinearLeastSquares" as a method I have the option to set a lower limit to the fit. This is driving me crazy.. I need to get the lower limit to the fit since the function I am really using in my code -log(a^x+b^x)/log(2) calculates complex values when x is a negative integer, and a and b are negative and my code stops there. > > > > Thank You for your help. > > > > -Aino > > which ver of ML and the curve fitting tbx do you have(?)... > > us I just switched form 2009b to 2010a, my toolbox seems to be v2.2. Does this work with your Matlab? -Aino
From: Aino on 11 Jul 2010 09:39
I just tried this with the 2009b version and it doesn't work. I changed the LinearLeastSquares to NonlinearLeastSquares and that worked. I would have preferred the Linear one, but if this works than I guess that's fine.. If anybody figures that Linear problem out, please let me know. -Aino |