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Midhun
Posts:
8
Registered:
8/18/09


Help with bvp4c
Posted:
Sep 15, 2013 7:31 PM


Hi all,
I have a 2nd order equation given by:
C" + i/(C+ r) *( C/(C+r)  1 ) C'  k* C = 0
where C = C(x), i, r,k are constants.
Boundary conditions: C(0) = 1; C'(1) = 1/(1 + r/C).
I was trying to use bvp4c for this problem by converting them to a set of ODEs, but couldn't make out how to specify the 2nd boundary condition.
Set of ODEs:
C' = P P' = i/(C+r) * (C/C+r  1)*P +k*C
BCs : C(0) = 1; P(1) = i/(1+r/C)
My code:
solinit = bvpinit([0,1],[0,0]); sol = bvp4c(@deriv,@bcs,solinit); plot(sol.x,sol.y(1,:),'bx',sol.x,sol.y(2,:),'gx');
%
function dYdx = deriv(x,Y) i = 1;r = 1; k = 1; dYdx = zeros(2,1); dYdx(1) = Y(2); dYdx(2) = i/(Y(1)+r) * (Y(1)/(Y(1)+r)  1)*Y(2) + k * Y(1);
%
function res = bcs(ya,yb) i = 1; r = 1; res = [ ya(1)  1 ???? ];
Could anyone help me on I can specify the 2nd B.C which is a function of C ? Thanks in advance...



