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can anyone help me ?

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diadalina
diadalina on 2 Jun 2019
Closed: MATLAB Answer Bot on 20 Aug 2021
here is a code matlab of one degree differential equation, i want to plot the error method for different values of N, can anyone help me
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diadalina
diadalina on 2 Jun 2019
the error wich is equal to norm(the approchsolution-the exactsoltuion), i want to show the accuracy of the numerical method used here , my code doesn't work correctly !!

Answers (1)

Stephan
Stephan on 2 Jun 2019
Edited: Stephan on 2 Jun 2019
clear all;
clc;
close all;
N=[100,200,300,400];
hold on
for k=1:numel(N)
%%les données mathématiques
t = 0:1/(N(k)-1):1;
%les conditions initiales
c0=0;
%%résolution de notre système
[~,Y]=ode45(@systest,t,c0 );
sol_exacte=t.*exp(t);
subplot(2,1,1)
plot(t,Y(:,1),t,sol_exacte,'+')
legend('sol-app','sol-exacte')
err(k)=norm(Y(:,1)'-sol_exacte)
e=err(k);
end
hold off
subplot(2,1,2)
semilogy(N,err,'ob--')
legend('error')
function F=systest(t,Y)
F(1,1)=Y(1)+exp(t);
end

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