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Plotting a smooth curve

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Hi there,
I know some basics of matlab, though I'm new to it. I use it only when I need any plot.
Now, I have some data points (x,y), which I have attached here. This is from my model output.
I want to import this file into matlab and plot this as a 2D plot in X,Y. The most important thing is that I need a smooth curve as in the attached figure named "Want.jpg". If I normally plot these points in MS excel, what I'm getting is shown in the figure named "Getting.jpg" and I don't want a plot like this.
Can anyone help me. Thanks in advance.


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Accepted Answer

Meg Noah
Meg Noah on 13 Jan 2020
Edited: Meg Noah on 13 Jan 2020
First, I added a header to the xlsx file so readtable can be used properly.
myData = readtable('Data_help.xlsx');
hold on;
ywant = 0:0.01:1;
P = polyfit(myData.y,myData.x,6);
xwant = polyval(P,ywant);


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Meg Noah
Meg Noah on 13 Jan 2020
'v5cubic' is one of many interp1 options that matlab offers. I usually use 'pchip' or 'spline'. Check the documentation.
The smooth operator can operate just on the data:
x_smoothed = smooth(x);
or you can overwrite the default sliding window length, with a number, say, 7, to have it smooth over 7 elements:
x_smoothed = smooth(x, 7);
There are some other features. It's a great algorithm. I think I have the paper somewhere, it was published in a now defunct computer journal/magazine.
Muhammadhn Muhammadh Khalid
Oh it's the 1D interpolation. I have been looking at the documentation of 'interp'. Thanks Meg Noah.
'Smooth' seems an interesting operator. I'll look for that paper as well. Thanks.
Muhammadhn Muhammadh Khalid
Hi Meg Noah, I' m trying the same thing with the attached data set. But ending up in a more curvy plot. I need a smooth plot similar, but better, than the attached figure. Thanks

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