Solving differential equation - where is my mistake in my code?

function HW_3_Exercise_11_ode_solver()

%Firstly define the given parameters

beta = 0.8;   % Maximal expression rate
alpha =0.6;   % Degredation rate
K = 0.25;   % Activation coefficient
n = 4;      % a constant
C0 = 0.1;   %  Initial concentration at time 0,

[tvals1,cvals1] = ode45(@protein_eqn,[0, 15],C0);

C1 = 0.2;   % Another Initial concentration
[tvals2,cvals2] = ode45(@protein_eqn,[0, 15],C1);


figure3 = figure;
axes('Parent',figure3,'FontSize',12);
box('on');
hold('all');
plot(tvals1,cvals1);
hold on
plot(tvals2,cvals2);
title({'Solution to problem #5'},'FontSize',14);
xlabel({'{Time (sec)}'},'FontSize',14,'FontName','Times New Roman');
ylabel({'% Concentration (mols/m^3)'},'FontSize',14,'FontName','Times New Roman');


% Define the function

function dcdt = protein_eqn (C)

dcdt = beta*(C/K)^n/(1+(C/K)^n)- alpha*C;

end

end

But when I run, I obtain the error

Where is my mistake? I cannot handle it? Please le me know my mistake. Thanks

Answer 1

[Walter Roberson]

ode45() always passes at least two parameters to the ode function: current time, and the boundary conditions.

You are not required to use either of them in your code, but you must accept them:

function dcdt = protein_eqn(~,C)

[Zeynep Toprak]

Also, please can you give a suggestion for this question ? https://www.mathworks.com/matlabcentral/answers/701072-how-to-draw-plot-for-the-given-functions-to-confirm-it