plot smoothing to get a curve

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Lila wagou
Lila wagou on 10 Sep 2016
Commented: Star Strider on 10 Sep 2016
Hy how to use smooth option to get a curve plot
XA = 0:1:5
YA = 2.^XA
plot(XA,YA)

Accepted Answer

Star Strider
Star Strider on 10 Sep 2016
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.
  4 Comments
Star Strider
Star Strider on 10 Sep 2016
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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