Corrigés desexercices
171
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...
g=r*h*C(1:N+2);
a=1/2+1/2*coth(g/2) -1./g
B=diag(C(2:N+1))*(-diag(a(3:N+1),-1)+ diag(2*a(2:N+1)-1)...
+ diag(1-a(2:N),1));
M=A+r*h*B;
...
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10. CD9.m
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clear
tN=[40:3:60];
r=100;
for i=1:length(tN)
N=tN(i);
h=1/(N+1);
t=0:h:1;
F=h^2*f(r,t(2:N+1))’;
C=c(t)’;
A=2*diag(ones(N,1))-diag(ones(N-1,1),1)- diag(ones(N-1,1),-1);
g=r*h*C(1:N+2);
a=1/2+1/2*coth(g/2) -1./g
B=diag(C(2:N+1))*(-diag(a(3:N+1),-1)+ diag(2*a(2:N+1)-1)...
+ diag(1-a(2:N),1));
M=A+r*h*B;
V=M\F;
V=[0;V;0];
Uex=u(r,t)’;
taberr(i)=norm(V-Uex,inf)
end;
a=polyfit( log(tN+1), log(taberr),1);
plot( log(tN+1), log(taberr));
title([’pentedeelaadroitedeeregression::’...
, num2str(a(1))],’FontSize’,16)
xlabel(’log(N+1)’,’FontSize’,16)
ylabel(’log(Erreur)’,’FontSize’,16)
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