MATLAB: How plot the best fit curve

best curveplotsavitzky-golay filteringsgolayfilt

Hi all,

the attached fig shows the daily mean time series data. how can plot the best fit curve? thank you.

Best Answer

It depends on the result you want.

If you are fitting a model, you have to specify the model, and then do the linear or nonlinear regression. Plot the model with the estimated parameters with your data.

Another option is the Savitzky-Golay filter. This is essentially a low-pass filter that can smooth the noise in your signal.

Otherwise, I would do a Fourier transform, find the most prominent frequency (or frequencies, depending on the information you want from your data), then use the Signal Processing Toolbox designfilt function to create a filter to pass your frequencies-of-interest. Then, plot the filtered signal with your data.

Use the hold function to plot more than one set of data on the same axes.

Related Solutions

MATLAB: How to draw the fitted curve and find the initial slope of the attached plot

Try this:

D = readmatrix('Example.xlsx');
x = D(:,1);
y = D(:,2);
p = polyfit(x, y, 3);
yfit = polyval(p, x);
dp = polyder(p);
dyfit = polyval(dp,x(1));
bint = (yfit(1) - dyfit*x(1));
xinitslope = [x(1)-x(75), x(1)+x(75)]; 
yinitslope = dyfit*xinitslope + bint;
figure
plot(x, y)
hold on
plot(x, yfit, 'LineWidth',1.5)
plot(xinitslope, yinitslope, 'LineWidth',3)
hold off
grid
legend('Data', '3\circ Polynomial Fit', 'Initial Slope', 'Location','N')
text(xinitslope(1), yinitslope(1), sprintf('\\leftarrow Initial Slope = %7.2f',dyfit), 'HorizontalAlignment','left', 'VerticalAlignment','middle')

producing:

MATLAB: How to plot two seperate figures the left and right channels

Either:

figure
plot(t, y(:,1))
figure
plot(t, y(:,2))

or:

figure
subplot(2,1,1)
plot(t, y(:,1))
subplot(2,1,2)
plot(t, y(:,2))

depending on the result you want.

Best Answer

Related Solutions

MATLAB: How to draw the fitted curve and find the initial slope of the attached plot

MATLAB: How to plot two seperate figures the left and right channels

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