Reduce the length of the vector

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Mirzobek Malikov 2022-8-30

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https://ww2.mathworks.cn/matlabcentral/answers/1790815-reduce-the-length-of-the-vector

评论： Mirzobek Malikov 2022-8-30

I have two points B1(2.91, 8.05, 43.85), A1(23.97, 4.65, 25) and center(4.15, 1.11, 25). I draw a circle using these three points. Then from these points I have two vectors to get a normal vector from the center. From my data, the normal vector length is too long. I have normalized the normal vector but in the plot its angle was different, when i checked the dot( N-O1, A1-O1) or dot( N-O1, B1-O1) were nonzero.

Is there any function or an approach to reduce the length of it by saving it to be a normal vector.

The normal vector gained by using cross(B1-O1, A1-O1) command.

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Answer 1

Matt J 2022-8-30

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https://ww2.mathworks.cn/matlabcentral/answers/1790815-reduce-the-length-of-the-vector#answer_1037780

编辑：Matt J 2022-8-30

在 MATLAB Online 中打开

when i checked the dot( N-O1, A1-O1) or dot( N-O1, B1-O1) were nonzero.

You should be checking dot( N, A1-O1)

B1=[2.91, 8.05, 43.85]; 
A1=[23.97, 4.65, 25];
O1=[4.15, 1.11, 25];
N=normalize( cross(B1-O1, A1-O1) ,'n');
norm(N)
ans = 1
dot(N,A1-O1)
ans = 4.4409e-16
dot(N,B1-O1)
ans = -4.9960e-16