How can I calculate max and min in degree?

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Matthias
Matthias 2014-4-11
回答： Walter Roberson 2014-4-11
I've got an Array with my Phase Phi in degrees:[ 170°,179°,180°,-179°...] ranging from -180° to 180° and I want to calculate how much it drifts over time. My current method of
phi = [ 170,179,180,-179]
drift =max(phi)-min(phi)
doesn't work, because 180°-(-179°) = 359°, while it should be 11°(from 170° to -179°). The Problem is that degrees are a cylic(x°= (x-360)°) unit unlike most units.
Is the a smart way to calculate the maximum phase drift?
  2 个评论
Image Analyst
Image Analyst 2014-4-11
If it goes from 179 to -179, isn't that a difference of 2? From 179 to 180 is 1, and 180 is the same as -180, so then from -180 to -179 is another 1, for a total of 2. At least that's how I view it.
Matthias
Matthias 2014-4-11
It was a little confusing. I tried to fix that. Now you can enter the Example in Matlab

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回答（2 个）

Mischa Kim
Mischa Kim 2014-4-11
编辑：Mischa Kim 2014-4-11
How about
drift = max(abs(diff(phi)));
By the way, how do you get 11°? Is that from a different set of data points not shown in your vector above?
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Mischa Kim
Mischa Kim 2014-4-11
编辑：Mischa Kim 2014-4-11
Understood. Do you have access to the Statistics Toolbox?
phi = [170,179,180,-179]';
drift = max(pdist(phi + 360*(phi<0)));
Matthias
Matthias 2014-4-11
编辑：Matthias 2014-4-11
This seems to just shift the problem:
phi = [4,-4]';drift = max(pdist(phi + 360*(phi<0)))
drift =
352

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Walter Roberson
Walter Roberson 2014-4-11
Use unwrap() before the diff()

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