# What determines the vector length that BCFUN should returns?

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Jules on 4 Sep 2013
What determines the vector length that BCFUN should returns? Because i have this error in my code:
Error in calling BVP4C(ODEFUN,BCFUN,SOLINIT,P1,P2...): The boundary condition function BCFUN should return a column vector of length 2.
In the problem that i have to solve i need to satisfice 4 boundary conditions in a system of two equations. But matlab only allows me to have two. This is my code :
Main:
init=bvpinit(linspace(-10,0,10),@initEq5_7_);
sol=bvp4c(@rhsEq5_7,@bcEq5_7,init,[],c);
z=linspace(-10,0,100);
p=deval(sol,z);
hold on;
plot(z,p(1,:),'r--');
plot(z,p(2,:),'b');
---------------------
function v = initEq5_7_(x)
v = [ sin(x)
sin(x)];
-------------------------
function rhs=rhsEq5_7(x,y,c)
s=2;
mu=2;
k=1;
alpha=-(mu/(c^2-s^2));
beta=2*k/s;
rhs=[-alpha*y(1)*(c-s*(2*y(2)-1))
-beta*y(1)*(1-y(2))*y(2)];
---------------------------
function rhs=bcEq5_7(l,r,c)
ql=0.5;
qr=0.01;
rhs=[l(1)
r(1)
l(2)
r(2)
];
It doesn't make sense to me, because i have seen code with more boundary conditions than equations. Thanks in advance.