Find minimum and maximum points of a spline
in [Matlab]
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From: us on 10 Jul 2010 17:04 "Alex Pereira" <alexlopespereira(a)gmail.com> wrote in message <i1aipl$1m0$1(a)fred.mathworks.com>... > "us " <us(a)neurol.unizh.ch> wrote in message <i1af4l$nmh$1(a)fred.mathworks.com>... > > "Alex Pereira" <alexlopespereira(a)gmail.com> wrote in message <i18h5j$smb$1(a)fred.mathworks.com>... > > > I've fit some data to a spline function. Now, I need to find all maximum and minimum points of this function. Does any one knows how to do it? > > > Here follows a simple test code that I'm using. > > > Thank you very much. > > > Alex > > > > > > a=[0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 ]; > > > b=[1:size(a)]; > > > b = b(:); > > > a = a(:); > > > fo_ = fitoptions('method','SmoothingSpline','SmoothingParam',0.10000000000000000555); > > > ft_ = fittype('smoothingspline'); > > > cf_ = fit(b,a,ft_,fo_); > > > h_ = plot(cf_,'fit',0.95); %% this line only plots the result > > > > no reason to discuss this as your code does not work... > > > > us > > Sorry. Now it works. > > a=[0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 ]; > b=[1:size(a,2)]; > b = b(:); > a = a(:); > fo_=fitoptions('method','SmoothingSpline','SmoothingParam',0.10000000000000000555); > ft_ = fittype('smoothingspline'); > cf_ = fit(b,a,ft_,fo_); > h_ = plot(cf_,'fit',0.95); ok... now, why don't you use one of the many peak-finders available on the FEX(?)... us
From: Alex Pereira on 10 Jul 2010 21:41 "us " <us(a)neurol.unizh.ch> wrote in message <i1an85$q10$1(a)fred.mathworks.com>... > "Alex Pereira" <alexlopespereira(a)gmail.com> wrote in message <i1aipl$1m0$1(a)fred.mathworks.com>... > > "us " <us(a)neurol.unizh.ch> wrote in message <i1af4l$nmh$1(a)fred.mathworks.com>... > > > "Alex Pereira" <alexlopespereira(a)gmail.com> wrote in message <i18h5j$smb$1(a)fred.mathworks.com>... > > > > I've fit some data to a spline function. Now, I need to find all maximum and minimum points of this function. Does any one knows how to do it? > > > > Here follows a simple test code that I'm using. > > > > Thank you very much. > > > > Alex > > > > > > > > a=[0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 ]; > > > > b=[1:size(a)]; > > > > b = b(:); > > > > a = a(:); > > > > fo_ = fitoptions('method','SmoothingSpline','SmoothingParam',0.10000000000000000555); > > > > ft_ = fittype('smoothingspline'); > > > > cf_ = fit(b,a,ft_,fo_); > > > > h_ = plot(cf_,'fit',0.95); %% this line only plots the result > > > > > > no reason to discuss this as your code does not work... > > > > > > us > > > > Sorry. Now it works. > > > > a=[0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 ]; > > b=[1:size(a,2)]; > > b = b(:); > > a = a(:); > > fo_=fitoptions('method','SmoothingSpline','SmoothingParam',0.10000000000000000555); > > ft_ = fittype('smoothingspline'); > > cf_ = fit(b,a,ft_,fo_); > > h_ = plot(cf_,'fit',0.95); > > ok... > now, why don't you use one of the many peak-finders available on the FEX(?)... > > us I'm right now following your suggestion and trying to find a peak finder. Thank you very much. Alex
From: Alex Pereira on 12 Jul 2010 08:46
"Alex Pereira" <alexlopespereira(a)gmail.com> wrote in message <i1b7fg$3jj$1(a)fred.mathworks.com>... > "us " <us(a)neurol.unizh.ch> wrote in message <i1an85$q10$1(a)fred.mathworks.com>... > > "Alex Pereira" <alexlopespereira(a)gmail.com> wrote in message <i1aipl$1m0$1(a)fred.mathworks.com>... > > > "us " <us(a)neurol.unizh.ch> wrote in message <i1af4l$nmh$1(a)fred.mathworks.com>... > > > > "Alex Pereira" <alexlopespereira(a)gmail.com> wrote in message <i18h5j$smb$1(a)fred.mathworks.com>... > > > > > I've fit some data to a spline function. Now, I need to find all maximum and minimum points of this function. Does any one knows how to do it? > > > > > Here follows a simple test code that I'm using. > > > > > Thank you very much. > > > > > Alex > > > > > > > > > > a=[0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 ]; > > > > > b=[1:size(a)]; > > > > > b = b(:); > > > > > a = a(:); > > > > > fo_ = fitoptions('method','SmoothingSpline','SmoothingParam',0.10000000000000000555); > > > > > ft_ = fittype('smoothingspline'); > > > > > cf_ = fit(b,a,ft_,fo_); > > > > > h_ = plot(cf_,'fit',0.95); %% this line only plots the result > > > > > > > > no reason to discuss this as your code does not work... > > > > > > > > us > > > > > > Sorry. Now it works. > > > > > > a=[0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 ]; > > > b=[1:size(a,2)]; > > > b = b(:); > > > a = a(:); > > > fo_=fitoptions('method','SmoothingSpline','SmoothingParam',0.10000000000000000555); > > > ft_ = fittype('smoothingspline'); > > > cf_ = fit(b,a,ft_,fo_); > > > h_ = plot(cf_,'fit',0.95); > > > > ok... > > now, why don't you use one of the many peak-finders available on the FEX(?)... > > > > us > > I'm right now following your suggestion and trying to find a peak finder. > Thank you very much. > Alex I could not find any peak finder that find it in a spline function. Then I searched other ways. Here follows the solution I found. a=[0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 ]; b=[1:size(a,2)]; b = b(:); a = a(:); fo=fitoptions('method','SmoothingSpline','SmoothingParam',0.10000000000000000555); ft = fittype('smoothingspline'); cf = fit(b,a,ft,fo); h = plot(cf,'fit',0.95); fx = differentiate(cf, b); fx2=fx; fx2(fx2>0)=1; fx2(fx2<0)=0; find(diff(fx2)~=0) Thank you very much. Alex |