MATLAB: Hello, I am having trouble plotting this graph. Whenever I run the code I get an error that I am not using the plot function correctly or I get a blank graph. I think it may have to do with how I solved the equation for T. Thanks for any help.

plotting

To = 273

Pair = 400000

Vo = .00066667

cp = 1

syms T t

T = To – (Pair*((Vo*((T/To)^(-5/2))) – Vo)/cp)*t;

Eqn = solve(T, t)

t = 0:.001:1;

Teq = Eqn

plot(t,Teq)

Best Answer

You are using the wrong plot function.

Use fplot instead:

fplot(Teq,[0 1])
xlabel('t')
ylabel('Teq')

EDIT — (27 Sep 2020 at 18:04)

Added plot image —

Related Solutions

MATLAB: Question about plotting graph.

For some T values, there are two solutions; which one you get depends upon the starting point for your search.

t0 = linspace(273, 500, 350);
nt = length(t0);
syms T1 T0 real
U = 8000;  % cal/(min*C)
Cp0 = 50;  % cal/(mol*C)
Fa0 = 80;  % 80mol/min
E = 40000; % cal/mol

H = -7500; % cal/mol
t = 100;    % min^-1 
%T0 = 450;   % K
Ta = 300;   % K

T2 = 350;   % K
R = 1.987;   % cal/(mol*K)
k2 = 6.6*10^-3; % min^-1
%Heat removed
k = U/(Cp0*Fa0);
Tc = (k*Ta+T0)/(1+k);
Rt = Cp0*(1+k)*(T1-Tc);
%Heat generated
k1 = k2*exp((E/R)*((1/T2)-(1/T1)));
Gt = -H*t*k1/(1+(t*k1));
eqns = subs(Rt == Gt, T0, t0);
y = zeros(1, nt);
old = 200;
for K = 1 : nt
    sol = double(vpasolve(eqns(K), T1, old));
    if isempty(sol)
        y(K) = nan;
    else
        y(K) = sol;
        old = sol;
    end
end
plot(t0, y, 'b-')
y1 = zeros(1, nt);
old = 500;
for K = 1 : nt
    sol = double(vpasolve(eqns(K), T1, old));
    if isempty(sol)
        y1(K) = nan;
    else
        y1(K) = sol;
        %old = sol;

    end
end
plot(t0, y1, 'b-')
y2 = zeros(1, nt);
old = 350;
for K = 1 : nt
    sol = double(vpasolve(eqns(K), T1, old));
    if isempty(sol)
        y2(K) = nan;
    else
        y2(K) = sol;
        %old = sol;
    end
end
plot(t0, y2, 'b-')

MATLAB: Plotting a graph.

s=[10, 12, 14;20, 22, 24;40, 44, 48].';
errorbar(mean(s),std(s))
ylim([5 50])
set(gca,'xtick',1:3,'xticklabel',num2str([1:3].','S%d'))

produces

Best Answer

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MATLAB: Question about plotting graph.

MATLAB: Plotting a graph.

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