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where is the fault the code is not running as it has two delays with four variables?

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Akhtar Jan
Akhtar Jan 2022-8-29
评论： Akhtar Jan 2022-8-30
function sol = exam4
options = ddeset('Events',@exam4e);
sol = dde23(@exam4f,[1, 10],[5; 0.1; 1],[0, 40],options);
xe = sol.xe;
ye = sol.ye;
ie = sol.ie;
n1 = find(ie == 1);
x1 = xe(n1);
y1 = ye(1,n1);
n2 = find(ie == 2);
x2 = xe(n2);
y2 = ye(2,n2);
n3 = find(ie == 3);
x3 = xe(n3);
y3 = ye(3,n3);
figure
plot(sol.x,sol.y,'k',x1,y1,'rs',x2,y2,'rs',x3,y3,'rs')
title('Infectious disease model from Hairer et alia.')
xlabel('Maxima are indicated by red squares.')
function yp = exam4f(x,y,Z)
ylag1 = Z(:,1);
ylag2 = Z(:,2);
k1 = 2;
k_1 = 1;
k2 = 1;
k3 = 1;
k_3 = 1;
k4 = 2;
k5 = 1;
k6 =1.5;
E1 = 1;
E2 = 2;
yp = [-k1*y(1)*E1+k_1*y(2)+k4*y(3);
k1*y(1)*E1-(k_1+k2)*y(2)-k5*ylag1(1);
k3*y(4)*E2-(k_3+k4)*y(3)-k6*ylag2(2);
k2*y(2)+k_3*y(3)-k3*y(4)*E2+k5*ylag1(1)+k6*ylag2(2)];
function [value,isterminal,direction] = exam4e(x,y,Z)
value = exam4f(x,y,Z,);
isterminal = zeros(3,1);
direction = -ones(3,1);
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采纳的回答

Torsten
Torsten 2022-8-29
Ran in:
sol = exam4()
sol = struct with fields:
solver: 'dde23' history: [4×1 double] discont: [0 1 2 3 10 11 12 20 21 30] x: [0 0.0017 0.0100 0.0404 0.0799 0.1286 0.1870 0.2568 0.3408 0.4446 0.5812 0.7631 1 1.0705 1.1411 1.2412 1.3637 1.5238 1.7619 2 2.3612 2.6806 3 3.5036 4.1851 4.7974 5.4500 6.0327 6.5176 7.0104 7.5991 8.3186 9.1593 10 10.1250 10.2500 … ] y: [4×93 double] xe: [0.8619 2.1568 2.8145 3.9275 4.0992 4.4285 4.8781 5.0578 5.6089 5.6448 6.2286 6.2739 6.7236 6.9830 7.4267 7.4846 8.3411 8.3953 9.2627 9.2852 10.0491 11.1232 12.9423 13.3956 14.3223 15.1159 15.4958 15.6244 16.0784 16.1023 16.6493 16.6748 … ] ye: [4×95 double] ie: [3 1 2 3 4 1 3 2 1 4 3 2 1 4 3 2 4 1 2 3 1 3 4 3 1 2 1 4 2 3 1 4 3 2 1 4 3 2 1 4 3 2 4 1 3 2 1 3 1 4 2 3 1 4 3 2 1 4 3 2 1 4 3 2 1 4 2 3 1 3 2 4 2 3 4 1 3 2 1 3 2 1 4 2 3 1 4 3 2 1 4 3 2 1 4] stats: [1×1 struct] yp: [4×93 double]
function sol = exam4
options = ddeset('Events',@exam4e);
sol = dde23(@exam4f,[1, 10],[5; 0.1; 1; 7],[0, 40],options);
xe = sol.xe;
ye = sol.ye;
ie = sol.ie;
n1 = find(ie == 1);
x1 = xe(n1);
y1 = ye(1,n1);
n2 = find(ie == 2);
x2 = xe(n2);
y2 = ye(2,n2);
n3 = find(ie == 3);
x3 = xe(n3);
y3 = ye(3,n3);
figure
plot(sol.x,sol.y,'k',x1,y1,'rs',x2,y2,'rs',x3,y3,'rs')
title('Infectious disease model from Hairer et alia.')
xlabel('Maxima are indicated by red squares.')
end
function yp = exam4f(x,y,Z)
ylag1 = Z(:,1);
ylag2 = Z(:,2);
k1 = 2;
k_1 = 1;
k2 = 1;
k3 = 1;
k_3 = 1;
k4 = 2;
k5 = 1;
k6 =1.5;
E1 = 1;
E2 = 2;
yp = [-k1*y(1)*E1+k_1*y(2)+k4*y(3);
k1*y(1)*E1-(k_1+k2)*y(2)-k5*ylag1(1);
k3*y(4)*E2-(k_3+k4)*y(3)-k6*ylag2(2);
k2*y(2)+k_3*y(3)-k3*y(4)*E2+k5*ylag1(1)+k6*ylag2(2)];
end
function [value,isterminal,direction] = exam4e(x,y,Z)
value = exam4f(x,y,Z);
isterminal = zeros(4,1);
direction = -ones(4,1);
end

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