why does the figure doesnt show the two vectors?
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Hi! i am working on a project using the while loop (similar to my question regarding for loop) the figure doesnt show the plot as desired. what is wrong regarding the code?
code below:
%Links length
L1=5; L2=1; L3=5; L4=7; AP=5;
% ternary link angle (degree)
delta=50;
th2= 0:1.2:360;
range_th2=300;
RP=zeros(1,range_th2);
RA=zeros(1,range_th2);
i=1;
while i<=301
% the loop variables
R1=L1;
R2=L2*(cos(th2(i))+sin(th2(i))*1i);
Z=R1-R2;
Zconj=conj(Z);
% Quadratic equation parameters
a=L4.*Zconj;
b=Z.*Zconj+L4.^2-L3.^2;
c=L4*Z;
T=roots([a b c]);
T_pos=T(2);
%T_pos=(-b+sqrt(b.^2-4.*c.*a))/(2.*a);
S=(L4*T_pos+Z)/L4;
% solution
th3(i)=rad2deg(angle(T_pos));
th4(i)=rad2deg(angle(S));
R3=L3*(cos(th3(i))+sin(th3(i))*1i);
R4=L4*(cos(th4(i))+sin(th4(i))*1i);
thAP=th3(i)-delta;
RAP=AP*(cos(thAP)+sin(thAP)*1i);
%position of A and P
RA(i)=R2;
RP(i)=R2+RAP;
i=i+1;
end
A_real=real(RA)
A_imag=imag(RA)
plot(A_real,A_imag)
hold on
P_real=real(RP)
P_imag=imag(RP)
plot(P_real,P_imag)
Answers (2)
Les Beckham
on 2 Nov 2023
Edited: Les Beckham
on 2 Nov 2023
It looks like it is working to me (see below). What are you expecting and how is that different from the results you are seeing?
%Links length
L1=5; L2=1; L3=5; L4=7; AP=5;
% ternary link angle (degree)
delta=50;
th2= 0:1.2:360;
range_th2=300;
RP=zeros(1,range_th2);
RA=zeros(1,range_th2);
i=1;
while i<=301
% the loop variables
R1=L1;
R2=L2*(cos(th2(i))+sin(th2(i))*1i);
Z=R1-R2;
Zconj=conj(Z);
% Quadratic equation parameters
a=L4.*Zconj;
b=Z.*Zconj+L4.^2-L3.^2;
c=L4*Z;
T=roots([a b c]);
T_pos=T(2);
%T_pos=(-b+sqrt(b.^2-4.*c.*a))/(2.*a);
S=(L4*T_pos+Z)/L4;
% solution
th3(i)=rad2deg(angle(T_pos));
th4(i)=rad2deg(angle(S));
R3=L3*(cos(th3(i))+sin(th3(i))*1i);
R4=L4*(cos(th4(i))+sin(th4(i))*1i);
thAP=th3(i)-delta;
RAP=AP*(cos(thAP)+sin(thAP)*1i);
%position of A and P
RA(i)=R2;
RP(i)=R2+RAP;
i=i+1;
end
A_real=real(RA);
A_imag=imag(RA);
plot(A_real,A_imag);
hold on
P_real=real(RP);
P_imag=imag(RP);
plot(P_real,P_imag)
axis equal
2 Comments
shamma aljaberi
on 2 Nov 2023
Les Beckham
on 2 Nov 2023
I edited my answer to add "axis equal" so the x and y scales are equal. They are both pretty circular in shape. Have you double checked the equations?
%Links length
L1=5; L2=1; L3=5; L4=7; AP=5;
% ternary link angle (degree)
delta=50;
th2= 0:1.2:360;
range_th2=300;
RP=zeros(1,range_th2);
RA=zeros(1,range_th2);
i=1;
while i<=301
% the loop variables
R1=L1;
R2=L2*(cos(th2(i))+sin(th2(i))*1i);
Z=R1-R2;
Zconj=conj(Z);
% Quadratic equation parameters
a=L4.*Zconj;
b=Z.*Zconj+L4.^2-L3.^2;
c=L4*Z;
T=roots([a b c]);
T_pos=T(2);
%T_pos=(-b+sqrt(b.^2-4.*c.*a))/(2.*a);
S=(L4*T_pos+Z)/L4;
% solution
th3(i)=rad2deg(angle(T_pos));
th4(i)=rad2deg(angle(S));
R3=L3*(cos(th3(i))+sin(th3(i))*1i);
R4=L4*(cos(th4(i))+sin(th4(i))*1i);
thAP=th3(i)-delta;
RAP=AP*(cos(thAP)+sin(thAP)*1i);
%position of A and P
RA(i)=R2;
RP(i)=R2+RAP;
i=i+1;
end
A_real=real(RA);
A_imag=imag(RA);
plot(A_real,A_imag);
hold on
P_real=real(RP);
P_imag=imag(RP);
plot(P_real,P_imag);
axis equal
legend('A','P')
figure, subplot(2,1,1) % look versus order instead
plot(A_real), hold on, plot(A_imag)
xlim([1 100])
legend('A_R','A_I')
subplot(2,1,2) % look versus order instead
plot(P_real), hold on, plot(P_imag)
legend('P_R','P_I')
xlim([1 100])
What we observe is that the "A" traces are pretty clean sinusoids with just a phase difference; hence the real vs imaginary parts follow a decent trace as shown on the first.
On the other hand, the "P" traces are much more random appearing; movements aren't smooth from one observation to the next; hence the two plotted against each other reflect that...
What you were expecting is unknown to us...we don't know the problem statement.
4 Comments
shamma aljaberi
on 2 Nov 2023
dpb
on 2 Nov 2023
Well, that'll all be dependent upon the path taken or the change in th based on the new solution each iteration.
One thing I notice that would make me wonder is
% solution
th3(i)=rad2deg(angle(T_pos));
th4(i)=rad2deg(angle(S));
R3=L3*(cos(th3(i))+sin(th3(i))*1i);
R4=L4*(cos(th4(i))+sin(th4(i))*1i);
in which you convert th from radians to degrees but then call sin/cos on them instead of using sind/cosd.
Are you sure that's what you intended?
Fixing the degree/radian units issue, based on @dpb's observation, produces a more interesting plot. Maybe that's closer to what's intended, @shamma aljaberi?
%Links length
L1=5; L2=1; L3=5; L4=7; AP=5;
% ternary link angle (degree)
delta=50;
th2= 0:1.2:360;
range_th2=300;
RP=zeros(1,range_th2);
RA=zeros(1,range_th2);
i=1;
while i<=301
% the loop variables
R1=L1;
R2=L2*(cos(th2(i))+sin(th2(i))*1i);
Z=R1-R2;
Zconj=conj(Z);
% Quadratic equation parameters
a=L4.*Zconj;
b=Z.*Zconj+L4.^2-L3.^2;
c=L4*Z;
T=roots([a b c]);
T_pos=T(2);
%T_pos=(-b+sqrt(b.^2-4.*c.*a))/(2.*a);
S=(L4*T_pos+Z)/L4;
% solution
th3(i)=rad2deg(angle(T_pos));
th4(i)=rad2deg(angle(S));
R3=L3*(cosd(th3(i))+sind(th3(i))*1i);
R4=L4*(cosd(th4(i))+sind(th4(i))*1i);
thAP=th3(i)-delta;
RAP=AP*(cosd(thAP)+sind(thAP)*1i);
%position of A and P
RA(i)=R2;
RP(i)=R2+RAP;
i=i+1;
end
A_real=real(RA);
A_imag=imag(RA);
plot(A_real,A_imag)
hold on
P_real=real(RP);
P_imag=imag(RP);
plot(P_real,P_imag)
axis equal
legend('A','P')
figure, subplot(2,1,1) % look versus order instead
plot(A_real), hold on, plot(A_imag)
xlim([1 100])
legend('A_R','A_I')
subplot(2,1,2) % look versus order instead
plot(P_real), hold on, plot(P_imag)
legend('P_R','P_I')
xlim([1 100])
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