unable to plot graphs

I have following code want cp Vs ct plot. How to plot it

clc;

clear all;

close all;

format long;

syms cp positive

for ct=0:0.05:1;

eqn = (1.38/(cp/ct)^2)-0.4151-(ct^3/cp^2) == 0

Root=vpasolve(eqn,cp,[0 1])

end

Answer 1

[Star Strider]

Try this:

format long;
syms cp positive 
ctv=0:0.05:1;
for k = 1:numel(ctv)
    ct = ctv(k);
    eqn = (1.38/(cp/ct)^2)-0.4151-(ct^3/cp^2);
    Root{k}=double(vpasolve(eqn,cp,[0 1]));
end
Root{cellfun(@isempty, Root)} = NaN;

figure
plot(ctv, [Root{:}])
grid

.

[Aiden James]

Hi sir, sorry for late comment. I have tried above code but it is showing following error. I am using matlab version 2015

Error using sym/subsasgn

Invalid indexing assignment.

Error in Untitled13 (line 7)

Root{k}=double(vpasolve(eqn,cp,[0 1]));

[Star Strider]

It runs without error in R2020a. I no longer have access to any R2015 version.

If you run my code exactly as I wrote it, it should work.

[Aiden James]

Hello sir, I just removed data type "double" from code. Now it is giving correct graph as expected. Thanks for your help. I may need more help in upcoming 1-2 months. Thanks agian.

[Star Strider]

As always, my pleasure!

[Aiden James]

sir,may be you can help me ,plesae refer following link for my query-

How to plot contour with constraints

https://in.mathworks.com/matlabcentral/answers/594670-how-to-plot-contour-with-constraints?s_tid=srchtitle