plot smoothing to get a curve

Question

Lila wagou 2016-9-10

1
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https://ww2.mathworks.cn/matlabcentral/answers/302561-plot-smoothing-to-get-a-curve

评论： Star Strider 2016-9-10

Hy how to use smooth option to get a curve plot

XA = 0:1:5
YA = 2.^XA
plot(XA,YA)

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Answer 1

Star Strider 2016-9-10

5
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/302561-plot-smoothing-to-get-a-curve#answer_234343

在 MATLAB Online 中打开

Use the linspace function to create ‘XA’:

XA = linspace(0,5);

This creates 100 (by default) regularly-spaced elements for ‘XA’ between 0 and 5.

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Lila wagou 2016-9-10

在 MATLAB Online 中打开

dear, why 50, and it does not work with the following data:

XA = [4,8,12,14,15,15.5,16,20]
YA = [100,400,100,200,150,175,160,160]

Star Strider 2016-9-10

在 MATLAB Online 中打开

The choice of 50 interpolation points is simply my choice.

It does work with those data:

XA = [4,8,12,14,15,15.5,16,20];
YA = [100,400,100,200,150,175,160,160];
x = XA;
y = YA;
xi = linspace(min(x), max(x), 150);                     % Evenly-Spaced Interpolation Vector
yi = interp1(x, y, xi, 'spline', 'extrap');
figure(1)
plot(x, y, 'bp')
hold on
plot(xi, yi, '-r')
hold off
grid
xlabel('X')
ylabel('Y')
legend('Original Data', 'Interpolation', 'Location', 'NE')

If it produces a different result than you get with Excel, it is because the interpolation method is different. The 'spline' method I used here may be correct, and Excel may be wrong. I have no idea what Excel uses. MATLAB offers several different interpolation methods, so choose the one that is most appropriate to your data.

Preferably, if you have an appropriate mathematical model of the process that produced your data, use it, and fit it to your data, rather than using interpolation.

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