# Why are the lines not showing up on my graphs?

6 views (last 30 days)
Anna Zito on 25 May 2020
Commented: Star Strider on 25 May 2020
g=9.81;
Ta=10;
mA=20;
for i=1:100
M=(i-1)*(30/99);
mB=4.05;
mC=M;
mD=M;
JC=0.005*M;
JD=JC;
JA=0.8055;
A=[mA 0 -1 1 0 0 0; (5*JA) 0 0.2 0 0 0 0; (10*JC) 0 0 -0.1 0 0.1 0; 0 mD 0 0 -1 -1 -1; 0 (10*JD) 0 0 0 -0.1 0.1; 0 mB 0 0 -1 0 0; -0.5 1 0 0 0 0 0];
B=[0; Ta; 0; (-mD*g); 0; (-mB*g); 0];
x=inv(A)*B;
aA(i)=x(1); aB(i)=x(2); FA(i)=x(3); TA(i)=x(4); TB(i)=x(5); TC(i)=x(6); TD(i)=x(7);
end
Mvector=linspace(0,30,100);
plot(Mvector, aA(i),'g',Mvector,aB(i),'b-.');
title('Acceleration');
legend('Disk A','Mass B');
xlabel('M (kg)');
ylabel('Acceleration (m/s^2)');
pause
plot(Mvector,aA(i),'g',Mvector,aB(i),'b-.');
title('Acceleration');
legend('Disk A','Mass M');
xlabel('M (kg)');
ylabel('acceleration (m/s^2)');
pause
plot(Mvector, FA(i),'k');
title('Plot 3');
xlabel('M (kg)');
ylabel('FA (N)');
pause
plot(Mvector,TA(i),'g',Mvector,TB(i),'b-.');
title('Plot 4');
legend('Cable A','Cable B');
xlabel('M (kg)');
ylabel('Tension (N))');
pause
plot(Mvector,TA(i),'g',Mvector,TC(i),'b:',Mvector,TD(i),'r-.');
title('Plot 5');
legend('Cable A','Cable C','Cable D');
xlabel('M (kg)');
ylabel('Tension (N)');
pause
plot(Mvector,FA(i)/(mA*g),'k');
title('Plot 6');
xlabel('M (kg)');
ylabel('mu');

Star Strider on 25 May 2020
You are only plotting one point (that being the last point) and it is not possible to plot lines with only one point.
Try this:
Mvector=linspace(0,30,100);
figure
plot(Mvector, aA,'g',Mvector,aB,'b-.');
title('Acceleration');
legend('Disk A','Mass B');
xlabel('M (kg)');
ylabel('Acceleration (m/s^2)');
% pause
figure
plot(Mvector,aA,'g',Mvector,aB,'b-.');
title('Acceleration');
legend('Disk A','Mass M');
xlabel('M (kg)');
ylabel('acceleration (m/s^2)');
% pause
figure
plot(Mvector, FA,'k');
title('Plot 3');
xlabel('M (kg)');
ylabel('FA (N)');
% pause
figure
plot(Mvector,TA,'g',Mvector,TB,'b-.');
title('Plot 4');
legend('Cable A','Cable B');
xlabel('M (kg)');
ylabel('Tension (N))');
% pause
figure
plot(Mvector,TA,'g',Mvector,TC,'b:',Mvector,TD(i),'r-.');
title('Plot 5');
legend('Cable A','Cable C','Cable D');
xlabel('M (kg)');
ylabel('Tension (N)');
% pause
figure
plot(Mvector,FA/(mA*g),'k');
title('Plot 6');
xlabel('M (kg)');
ylabel('mu');
Also, you were overplotting each new plot on the previous one, erasing the previous one. Since it appears you want them on separate figures, this slightly revised code does that. If you want to plot all of them on the sane axes, use the hold function.
Anna Zito on 25 May 2020
That worked!!! Thank you so much! Youre amazing!!!!!!
Star Strider on 25 May 2020
As always, my pleasure! Thank you!