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From: Rob on 22 Dec 2008 09:03
Can anybody help me with the following problem:

CODE

function test2

clc;clear;close all;

z=2;
solinit = bvpinit(linspace(0,z,50),ones(7,1));
sol = bvp4c(@ode,@bc,solinit);

function dydx = ode(x,y);
K = 100;
q = 5;
dydx = [ y(2)
y(3)
(1/K)*y(4)
q-(c*y(1))
y(6)
y(7)
(1/K)*y(8)
-c*y(5)
];
end

function res = bc(ya,yb)

res = [ya(2)
ya(4)
yb(1) - yb(5)
yb(2) - yb(6)
yb(3) - yb(7)
yb(4) - yb(8)
];
end

end

When I run this, it doesn't work because:
??? Attempted to access yb(8); index out of bounds because numel(yb)=7.

But when I use one(8,1) in solinit:
??? Error using ==> bvp4c at 194
The boundary condition function should return a column vector of length 8

How can I solve this problem?
From: Rob on 22 Dec 2008 11:40
I've made some mistakes, because I defined not all bc. My new code is:

function test2v2

clc;clear;close all;

xinit = [0, 0.25, 0.5, 1, 1, 1.25, 1.5, 1.75, 2];
yinit = ones(8,1);

solinit = bvpinit(xinit,yinit);
sol = bvp4c(@ode,@bc,solinit);

function dydx = ode(x,y,region);
c = 0.3;
K = 100;
q = 5;

dydx = [ y(2)
y(3)
(1/K)*y(4)
q-(c*y(1))
y(6)
y(7)
(1/K)*y(8)
-c*y(5)
];

end

function res = bc(YL,YR)

res = [YL(2,1)
YL(4,1)
YL(1,2) - YR(1,1)
YL(2,2) - YR(5,1)
YL(3,2) - YR(6,1)
YL(4,2) - YR(8,1)
YR(1,end)
YR(2,end)
];
end

end

But still this doesn't work:
??? Error using ==> bvparguments at 132
Error in calling BVP4C(ODEFUN,BCFUN,SOLINIT):
The boundary condition function BCFUN should return a column vector of length 16.

Error in ==> bvp4c at 120
[n,npar,nregions,atol,rtol,Nmax,xyVectorized,printstats] = ...

Error in ==> test2v2 at 9
sol = bvp4c(@ode,@bc,solinit)
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