Hi my name is Hidde and i am a first year IEM student,
I got an assignment where a part of it is to solve 2 differential equations and plot them in a graph. I just keep getting error and i cannot get the code to work.
I have some experience with matlab but i never used Ode45 before. I've read numerous tutorials and watched a bunch of video's but i really need help. Tamb is time dependant and changes every second.
OdeScript
% script for solving an ode45
clear allclc% define constants
R1 = 0.4;R2 = 0.3;Rwin = 0.5;Cint = 1.0 * 10^4;Cwall = 5.0 * 10^2; Tamb = dlmread('Team_82.dat');A = 1 / (Cwall*R2);B = 1 / (Cwall*R1);C = 1 / (Cint*R1);D = 1 / (Cint*Rwin);% time dependent window
tspan = linspace(0,1440,1441); % calculate from t=0 up to t=1440
y0 = [18 20]; % initial conditions
% define your ode-function
odefunc = @(t,dTempdt) odeFunction1(t,Twall, Tint, Tamb, A, B, C, D);[t,dTempdt] = ode45(odefunc, tspan, y0);% plot the results
plot(t,dTempdt)
OdeFunction
function [dTempdt] = odeFunction1(t,Twall, Tint, Tamb, A, B, C, D)% set of ordinary differential equations
% input: A - constant
% B - constant
% C - constant
% D - constant
% t - the time variable
% Tint - state variable
% Twall - state variable
%output: dTempdt - the set of equations
% initialize the set of equations
dTempdt = zeros(2,1);% define the set of equations
dTempdt(1) = A*Tamb - A*Twall + B*Tint - B*Twall;dTempdt(2) = C*Twall - C*Tint + D*Tamb - D*Tint;end
I am getting the folowing errors:
Undefined function or variable 'Twall'.Error in odeScript1>@(t,dTempdt)odeFunction1(t,Twall,Tint,Tamb,A,B,C,D)Error in odearguments (line 90)f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0.
Error in ode45 (line 115) odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);Error in odeScript1 (line 31)[t,dTempdt] = ode45(odefunc, tspan, y0);
Any help would be greatly appreciated!
Best Answer