disser1.pdf (2006 KB) - Ernst-Moritz-Arndt-Universität Greifswald

C. MATLAB-Programme
sol = bvpinit(linspace(0,20,50),[1 0 0]);
sol = bvp4c(@odesys2,@bc2,sol,options);
x = [sol.x];
y1 = [sol.y(1,:)]; y2 = [sol.y(2,:)]; y3 = [sol.y(3,:)];
y=[y1;y2;y3];
for i=1:size(y,2)
y4(i)=(0.00125)/(y(1,i)*(0.42375-y(2,i)* ...
0.000375*exp(0.06*y(3,i))));
end; y,
%plot(x,y1(1,:))
plot(y3,y4)
title(’Randwertproblem’)
xlabel(’t’)
ylabel(’u(t)’)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function dydx = odesys2(x,y,n)
% ODE function
dydx = [ 0.4*y(1)*(1-y(1))-(0.000375*0.00125/ ...
((0.42375-y(2)* ...
0.000375*exp(0.06*y(3)))))
((-0.42375*0.00125*exp(-0.06*y(3))) ...
/((y(1))*(0.42375-y(2)* ...
0.000375*exp(0.06*y(3)))))- ...
0.4*y(2)+2*0.4*y(2)*y(1)+ ...
((0.000375*0.00125*y(2))...
/((y(1))*(0.42375-y(2)* ...
0.000375*exp(0.06*y(3)))))
1];
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function res = bc2(ya,yb)
%Boundary conditions
res = [ ya(1)-0.25
yb(2)
ya(3)];
C.6. Programm 6. Newton-Methode für ein
nichtlineares Gleichungssystem.
clear all
syms x y
f1=-20*0.00125*x+0.25*(((-0.42375*0.1)/ ...
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