finding the slope and plotting it in graph

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sisir regmi 2019-4-20

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https://ww2.mathworks.cn/matlabcentral/answers/457521-finding-the-slope-and-plotting-it-in-graph

评论： David Wilson 2019-4-21

fourierademale.png

i need to find the x,y points and plot those points finding the slope making a line in x,y plane. How can i get it automatically

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Walter Roberson 2019-4-21

There are over 20 File Exchange contributions that do their best to return the line coordinates https://www.mathworks.com/matlabcentral/fileexchange?q=tag%3Adigitize

Your image might be too dense for it to work properly: you effectively have multiple y for each x because of low resolution.

David Wilson 2019-4-21

Are you sure you want the gradient of your data?

I should also comment that from your above (frequency?) plot, it does seem very noisy, and given that extracting the gradient operation tends to amplify the high frequency components, (especially if you do something crude like finite differences), then your resultant plot of the derivative will be very niosy.

If I was to smooth your data, I'd think very carefully about how to do it. I'd probably fit a smoothing spline through the data, and then differentiate that. But plotted over the range you have shown above, it's likely to be a considerable mess.

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