graph fitresult breaks weirdly in plot..?

hey,

I'm trying to plot this data like this:

x=[0.1, 0.5, 1, 1.5, 2.5, 3, 3.3, 3.5, 3.7, 4, 4.5, 5, 6, 8, 10, 15, 20, 30, 40, 50, 60, 65, 70, 75, 80, 90, 110, 250, 400, 650, 1000]*1e3;

y=[0.0351,0.1730,0.3280,0.4640,0.6552,0.7219,0.7547,0.7747,0.7927,0.8160,0.8488,0.8756,0.9160,0.9584,0.9798,1.0000,0.9997,0.9822,0.9517,0.9145,0.8749,0.8556,0.8355,0.8155,0.7957,0.7538,0.6800,0.3479,0.1913,0.0622,0.0416];

[xData, yData] = prepareCurveData( x, y);

ft = fittype( '((2*pi*x*a)/sqrt(1+(2*pi*x*a)^2))*(1/sqrt(1+(2*pi*x*b)^2))', 'independent', 'x', 'dependent', 'y' );

opts = fitoptions( 'Method', 'NonlinearLeastSquares' );

opts.Display = 'Off';

opts.Lower = [-Inf 1e-06];

opts.StartPoint = [0.107005609113855 0.921912151588772];

opts.Upper = [Inf 3e-06];

[fitresult, gof] = fit( xData, yData, ft, opts );

figure( 'Name', 'untitled' );

h = semilogx( xData, yData , '.');

hold on;

plot( fitresult);

somehow, matlab creates this break in the fitresult, and ignores the second dot in the data.

can you help me understand why and how to fix it?

Answer 1

[KALYAN ACHARJYA]

somehow, matlab creates this break in the fitresult, and ignores the second dot in the data?.

Second dot id the part of fitting curve.

Both are two different plot, fitting curve is with red points as shown in following code

x=[0.1, 0.5, 1, 1.5, 2.5, 3, 3.3, 3.5, 3.7, 4, 4.5, 5, 6, 8, 10, 15, 20, 30, 40, 50, 60, 65, 70, 75, 80, 90, 110, 250, 400, 650, 1000]*1e3;
y=[0.0351,0.1730,0.3280,0.4640,0.6552,0.7219,0.7547,0.7747,0.7927,0.8160,0.8488,0.8756,0.9160,0.9584,0.9798,1.0000,0.9997,0.9822,0.9517,0.9145,0.8749,0.8556,0.8355,0.8155,0.7957,0.7538,0.6800,0.3479,0.1913,0.0622,0.0416];
[xData,yData]=prepareCurveData(x,y);
ft=fittype('((2*pi*x*a)/sqrt(1+(2*pi*x*a)^2))*(1/sqrt(1+(2*pi*x*b)^2))', 'independent', 'x', 'dependent', 'y' );
opts=fitoptions( 'Method','NonlinearLeastSquares' );
opts.Display='Off';
opts.Lower=[-Inf 1e-06];
opts.StartPoint=[0.107005609113855 0.921912151588772];
opts.Upper=[Inf 3e-06];
[fitresult,gof]=fit(xData,yData,ft,opts );
figure('Name','untitled');
h=semilogx(xData,yData,'.');
hold on;
plot(fitresult,'r*');
grid on;