Plotting multiple figures: one figure doesnt show and the other is wrong

vo=10;      %%dm^3/min
T=27+273.15;       %%k
p=4;        %%atm
R=82060;    %%dm^3*atm/(k*mol)
k1=.004;    %%(mol/dm^3)^.5*min
k2=.3;      %%min^-1
k3=.25;     %%DM^3/MOL*MIN
cao=p/(R*T);
ca=linspace(cao,.000005);
rx=k1*ca.^(1/2);
rb=k2*ca;
ry=k3*ca.^2;
sby=rb./ry;
sbx=rb./rx;
sbxy=rb./(rx+ry);
plot(ca,sbx,ca,sby,ca,sbxy)

%%hold on
%%plot(ca,sby)
%%plot(ca,sbxy)

xlabel('Ca')
title('Sb/y,Sb/x,Sb/xy Vs. Ca')
legend({'Sb/x','Sb/y','Sb/xy'},'Location','Southwest')

[Tommy]

Only one figure shows because you only call plot once. What about the figure is wrong?

[Rodrigo Blas]

%% problem6 part a 
vo=10;      %%dm^3/min
T=27+273.15;       %%k
p=4;        %%atm
R=82060;    %%dm^3*atm/(k*mol)
k1=.004;    %%(mol/dm^3)^.5*min
k2=.3;      %%min^-1
k3=.25;     %%DM^3/MOL*MIN
cao=p/(R*T);
ca=linspace(cao,.000005);
rx=k1*ca.^(1/2);
rb=k2*ca;
ry=k3*ca.^2;
sby=rb./ry;
sbx=rb./rx;
sbxy=rb./(rx+ry);

plot(ca,sbx)
hold on
plot(ca,sby)
hold on
plot(ca,sbxy)
hold off

xlabel('Ca')
title('Sb/y,Sb/x,Sb/xy Vs. Ca')
legend({'Sb/x','Sb/y','Sb/xy'},'Location','Southwest')

%%prob 6 part b

I tried using hold on

plot(ca,sbx)--> this plot doesnt show

plot(ca,sby)--> this is right

plot(ca,sbxy)--> This one is a straight horizontal line at zero(incorrect)

[Tommy]

Oh I see. All three are actually showing, but sbx and sbxy are very close in value, so sbx is hard to see. Use

plot(ca,sbx,'*')
hold on
plot(ca,sby)
hold on
plot(ca,sbxy)
hold off

if you want to verify.

Further, sbx and sbxy only appear to be horizontal lines at 0. Use

plot(ca,sbx,'*')
hold on
%plot(ca,sby)
hold on
plot(ca,sbxy)
hold off

to see that they are indeed curves.

Are you sure your calculations are correct?

[David Hill]

And sbxy is not a line. Try plotting it all by itself (its amplitude is very small).

[Rodrigo Blas]

Thank you!

Answer 1

[Guru Mohanty]

The three plots are not visible due to following reasons-

1. The difference between ‘sbx’ and ‘sbxy’ lies in the range of 10-7 . Although there are two different plots but its looks like single due to very less difference in values.
2. The min to max range of three plots are given as-

The range of ‘sby’ is much higher than that of both ‘sbx’ and ‘sbxy’. This is the reason why the plot sbxy looks like straight horizontal line at Zero, when three are plotted together.

The plotting should be done with different axes.