Error on using ODE45 and cannot prompt output

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Deck Zhan Sim
Deck Zhan Sim on 6 Jan 2022
Commented: Jan on 6 Jan 2022
Hi, i encounter some problem on showing the outputs for ODE45. May i know on how to solve it? I will be grateful that the solutions that provided. Thanks!
Here is the error message:
Error in p2 (line 13)
[t,C_calc]=ode45(first,timespan,C0);
Here is the codes:
clear
close all
clc
k=1000000000;
r = 4.31*(10^-3);
kt=0.9;
D=1;
timespan=[0 30]';
C0=40000;
first=@(t,C) (C*(r-((r-kt*d)/k)*C-(kt*D)));
[t,C_calc]=ode45(first,timespan,C0);
plot(t,C_calc)
hold on
  3 Comments
Ilya Gurin
Ilya Gurin on 6 Jan 2022
There's no way that can be the full text.

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Answers (1)

Jan
Jan on 6 Jan 2022
I get a different error message, which is very clear:
k=1e9;
r = 4.31e-3;
kt=0.9;
D=1;
timespan=[0 30]';
C0=40000;
first=@(t,C) (C*(r-((r-kt*d)/k)*C-(kt*D)));
[t,C_calc]=ode45(first,timespan,C0);
Unrecognized function or variable 'd'.

Error in solution (line 7)
first=@(t,C) (C*(r-((r-kt*d)/k)*C-(kt*D)));

Error in odearguments (line 90)
f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0.

Error in ode45 (line 106)
odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);
plot(t,C_calc)
hold on
  2 Comments
Jan
Jan on 6 Jan 2022
As soonas I replace "d" by "D", the code runs and displays a diagram.

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