why cant i rotate the 2nd line at the X axis it takes reference as point 0,0 and rotates at 45 degree angle i want to rotate the line at same axis

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Prakash Choudhary 2019-4-6

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/454780-why-cant-i-rotate-the-2nd-line-at-the-x-axis-it-takes-reference-as-point-0-0-and-rotates-at-45-degre

评论： Prakash Choudhary 2019-4-6

采纳的回答： Walter Roberson

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Prakash Choudhary 2019-4-6

在 MATLAB Online 中打开

close all;
clc;
clear all;
x0=  [0 0];
y0=  [-85 85];
x1 = [820 820 ];
y1 = [ -85 85 ];
hold on
plot (x1,y1);
plot (x0,y0);
grid on
angle=45;
     angle_rad=((angle*2.*pi)./360);        
       [THETA,R] = cart2pol(x0,y0);
         THETA=THETA+angle_rad; %Add a_rad to theta
 [x0r,y0r] = pol2cart(THETA,R);
 plot(x0r,y0r);
 axis equal; %Rotated
 angle=45;
     angle_rad=((angle*2.*pi)./360); 
     [THETA,X] = cart2pol(x1,y1);%Convert to polar coordinates
     THETA=THETA+angle_rad; %Add a_rad to theta
      [x1r,y1r] = pol2cart(THETA,X); %Convert back to Cartesian coordinates
       plot(x1r,y1r);
       grid on
 hold off
  axis equal; %Rotated

Prakash Choudhary 2019-4-6

I am Just a biggner so i creat the code with code with theta.

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Answer 1

Walter Roberson 2019-4-6

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/454780-why-cant-i-rotate-the-2nd-line-at-the-x-axis-it-takes-reference-as-point-0-0-and-rotates-at-45-degre#answer_369325

It is rotating. Look at the top of your plot.

The way to rotate relative to a point is to subtract the coordinates of the point to rotate around, do the rotation, then add the coordinates of the point to rotate around back in. If you want ot rotate around (800,0) then cart2pol(x1-800,y1) and plot(x1r+800,y1r)