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2D matrix indexing for element wise operation

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Raj Raj
Raj Raj on 19 Feb 2016
Edited: Star Strider on 19 Feb 2016
Hello all, I am using following code to estimate pairwise angle between for a vector. Where the angle should be between 0 to 2*pi. I am able to predict the angle. But I need your advise on implementing this two for loops. This is slowing the code. Looking forward for your attention. In the code, XYdata is a n x 2 matrix representing the Cartesian coordinates of individual point [xi, yi]. I presume this slow is because of two FOR loops.
for i2 =1:length(XYdata_new)
for j2 = 1:length(XYdata_new)
angle_ij(i2,j2)= Angle360(XYdata_new(i2,1), XYdata_new(i2,2), XYdata_new(j2,1),XYdata_new(j2,2));
end
end
Thanks in advance.
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Accepted Answer

Star Strider
Star Strider on 19 Feb 2016
I would use the atan2 or atan2d functions. They are vectorised, so you can likely give your matrix columns to them directly and then do the angle difference calculations.
  8 Comments
Star Strider
Star Strider on 19 Feb 2016
My pleasure!
Thank you.
EDIT More efficient versions of the angle conversion lines are:
Angles360 = rem(360+a, 360);
Angles2pi = rem(2*pi+a, 2*pi);

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