Issue: Matrix Dimensions Must Agree

%PV=NRT
T1=273;
T2=293;
T3=313;
P=100:50:300; %kPa
R=8.314; %Ideal gas constant J*K^-1*mol^-1
n=1;

Volume1=n*R*T1/P;
Volume2=n*R*T2/P;
Volume3=n*R*T3/P;

figure(1)
plot(Volume1,P)
xlabel('Pressure [kPA]')
ylabel('Volume [m^3]')

figure(2)
plot(Volume2,P)
xlabel('Pressure [kPA]')
ylabel('Volume [m^3]')

figure(3)
plot(Volume3,P)
xlabel('Pressure [kPa]')
ylabel('Volume [m^3]')

Answer 1

[James Tursa]

Use element-wise operator ./ (with the dot) instead of the matrix operator /

E.g.,

Volume1=n*R*T1./P;
Volume2=n*R*T2./P;
Volume3=n*R*T3./P;

[Brandon Mello]

In the plots generated, how would you vary the pressure between 100 kPa and 300 kPa in steps of 50 kPa?

[James Tursa]

You've got the pressure and volume arguments reversed in your plot calls. The first one is the x-axis and the second one is the y-axis. So this line:

plot(Volume1,P)

should be this instead:

plot(P,Volume1)

Same for Volume2 and Volume3.

And if you want to change the tick spacing on the x-axis, you could do something like this for each figure:

set(gca,'Xtick',P);

Finally, I typically use this to make the plots more readable:

grid on