Reduce the length of the vector

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.

Answer 1

[Matt J]

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

[Mirzobek Malikov]

thanks, its good.

[Mirzobek Malikov]

but i wanna ask one more, is N has normal vector [nx, ny, nz] coordinates or last position of the normal vector? I need to plot the normal vector in the end

[Matt J]

Sorry, I don't follow. By nature, normal vectors have direction. They do not have "position".

[Mirzobek Malikov]

it's ok. i found the solution to for changing direction of the normal vector. Just multiply N with minus. dot(-N, A1-O1) give zero value.