Transform angles that are -180 to +180 to angles that are in the 0-360 degree range?

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I am implementing a vector coding technique in matlab using the atan2d(diff(y),diff(x)) function, but the results are from -180 to +180 and I would like to have a 0-360 range. I tried to input an if statement for angles < 0 to have 360 added to them, but I couldn't get it to work. It is possible that I just didn't write the statement correctly, but I would appreciate any tips or advice.
Kylie Davis
Kylie Davis on 1 Jun 2016
Sorry about that. I tried: if x < 0 x = x+360 end
But the other difficulty I am having is that I have so many data sets that I need to apply that to. I have hip, knee, and ankle joint angle data for both limbs of 18 subjects. So I need to have an if statement correcting the negative angles for 36 different sets.

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Accepted Answer

Star Strider
Star Strider on 1 Jun 2016
This is my little anonymous function that I use for such problems:
Angles360 = @(a) rem(360+a, 360); % For ‘atan2d’
Star Strider
Star Strider on 1 Jun 2016
My pleasure!
It’s an anonymous function, and works like any other function. Just put it at the beginning of your code, then call it as:
Angles360 = @(a) rem(360+a, 360); % For ‘atan2d’
x = randi(9, 5, 1); % Create Data
y = randi(9, 5, 1); % Create Data
theta = atan2d(diff(y),diff(x));
theta360 = Angles360(theta);

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More Answers (1)

theodore panagos
theodore panagos on 5 Dec 2018
A formula to calculate an angle counter clockwise from x positive to 360 degrees:
f(x,y)=180-90*(1+sign(x))* (1-sign(y^2))-45*(2+sign(x)*sign(y)


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