How to rotate a line drawn by two points by angle 0.1:0.1:1 using a for loop?

the points are (x(1) y(1)) and (x(2),y(2)). i dont have any code. I am new to coding in general and i am not sure how to rotate the plotted line using a for loop. I am not sure how to change the values in both vectors by that angle 0.1:0.1:1. Any help would be appreciated thanks.

Answer 1

[Voss]

Math reference: Rotation Matrix.

Rotation about point A:

a = [3 1];
b = [10 3];
angle = 0.1:0.1:1;

figure();
plot([a(1) b(1)],[a(2) b(2)],'LineWidth',2);
hold on
axis equal

text(a(1),a(2),'A','HorizontalAlignment','right');
text(b(1),b(2),'B','HorizontalAlignment','left');

for ii = 1:numel(angle)
    
    cos_angle = cos(angle(ii));
    sin_angle = sin(angle(ii));
    
    new_b = a(:)+[cos_angle -sin_angle; sin_angle cos_angle]*(b-a).';
    
    plot([a(1) new_b(1)],[a(2) new_b(2)],'k--');
    
    text(new_b(1),new_b(2),sprintf(' %.1f',angle(ii)));
    
end

ylim([0 9]);

title('Rotating AB about point A by different angles (in radians)');

Rotation about the origin:

a = [3 1];
b = [10 3];
angle = 0.1:0.1:1;

figure();
plot([a(1) b(1)],[a(2) b(2)],'LineWidth',2);
hold on
axis equal

text(a(1),a(2),'A','HorizontalAlignment','right');
text(b(1),b(2),'B','HorizontalAlignment','left');

for ii = 1:numel(angle)
    
    cos_angle = cos(angle(ii));
    sin_angle = sin(angle(ii));
    R = [cos_angle -sin_angle; sin_angle cos_angle];
    new_a = R*a(:);
    new_b = R*b(:);
    
    plot([new_a(1) new_b(1)],[new_a(2) new_b(2)],'k--');
    text(new_b(1),new_b(2),sprintf(' %.1f',angle(ii)));
    
end

ylim([0 11]);

title('Rotating AB about the Origin by different angles (in radians)');

[Owen Bennett]

Really appreciate it!!

[Voss]

No problem!

[Ham Man]

Voss I have the same problem and in my case a and b have 128 elements. How this works for my case?should I define a new matrix R?

I need all new points in new line.

Many thanks in advance!