Why is an extra line being plotted?
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Joshua Tsui
on 12 Mar 2021
Commented: Alan Stevens
on 12 Mar 2021
Hello,
I have been trying to display the deflection and displacement of beams within a building. Currently, I am having an issue from within my loop which plots the displacement of each floor.
As you can see from the plot below, I have a red horizontal line from (0,0) to(2,0). Why is this? I think I have done something wrong in my "Displacement" loop but I am not sure
numFlr=2
Phi_EigVec=[1 3;2 -3;]
y1=zeros(numFlr,1);
y2=zeros(numFlr,1);
x1=zeros(numFlr,1);
x2=Phi_EigVec(:,1);
%Displacement
hold on
for i=1:numFlr
y1(i)=i
y2(i)=i
A = [x1(:) x2(:)]; B = [y1(:) y2(:)];
plot(A.',B.','r')
end
%Beam Deflection
AZero=[0]
BZero=[0]
AEven=A(:,2:2:end);
BEven=B(:,2:2:end);
AFull=[AZero,AEven']
BFull=[BZero,BEven']
plot(AFull.',BFull.','g')
%Vertical Line
y=numFlr
line([0,0],[0,y])
%Axis
axis([-5 5 -1 5])
3 Comments
Adam Danz
on 12 Mar 2021
Edited: Adam Danz
on 12 Mar 2021
You just need to move the two commented lines outside of the loop. Alan Stevens's answer does this (though, no need for the 2nd "hold on").
hold on
for i=1:numFlr
y1(i)=i
y2(i)=i
% A = [x1(:) x2(:)]; B = [y1(:) y2(:)];
% plot(A.',B.','r')
end
UPDATE
Actually, you don't need the loop at all,
y1 = 1:numFlr;
y2 = y1;
A = [x1(:) x2(:)]; B = [y1(:) y2(:)];
hold on
plot(A.',B.','r')
Accepted Answer
Alan Stevens
on 12 Mar 2021
More like this, I think:
numFlr=2;
Phi_EigVec=[1 3;2 -3;];
y1=zeros(numFlr,1);
y2=zeros(numFlr,1);
x1=zeros(numFlr,1);
x2=Phi_EigVec(:,1);
%Displacement
hold on
for i=1:numFlr
y1(i)=i;
y2(i)=i;
end
A = [x1(:) x2(:)]; B = [y1(:) y2(:)];
plot(A(1,:),B(1,:),'r',A(2,:),B(2,:),'r')
hold on
%Beam Deflection
AZero=[0];
BZero=[0];
AEven=A(:,2:2:end);
BEven=B(:,2:2:end);
AFull=[AZero,AEven'];
BFull=[BZero,BEven'];
plot(AFull.',BFull.','g')
%Vertical Line
y=numFlr;
line([0,0],[0,y])
%Axis
axis([-5 5 -1 5])
3 Comments
Alan Stevens
on 12 Mar 2021
Extend the plot command
plot(A(1,:),B(1,:),'r',A(2,:),B(2,:),'r',A(3,:),B(3,:),'r')
Alan Stevens
on 12 Mar 2021
More generally
for i = 1:numFlr
plot(A(i,:),B(i,:),'r')
end
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