ode45- must return a column vector (Thanks in advance for help)

iSCRIPT
function dMdx=s(x,M,gamma_b,a1Vec,b1Vec,xVec)
a1=interp1(a1Vec,xVec);
b1=interp1(b1Vec,xVec);
dMdx= M*((1+((gamma_b-1)/2)*M^2)/(1-M^2))*(-a1+((1+(gamma_b*M^2))/2)*b1);
end

COMMAND WINDOW

    >> x=0:0.001:0.35;
xVec=0:0.01:0.35;
xi=xVec(1);
x4=xVec(end);
gamma_b=1.36;
X=((x-xi)/(x4-xi));
a3=0.0038;
A=a3*(1+X);
a=gradient(A,x);
a1Vec=a./A;
tau_b=1.4;
theta=2;
Tt2=2200;
Ttx=Tt2*(1+(tau_b-1)*((theta*X)./(1+(theta-1)*X)));
b=gradient(Ttx,x);
b1Vec=b./Ttx;
initial_M=2;
[x,M]=ode45(@(x,M)s(x,M,gamma_b,a1Vec,b1Vec,xVec),[xi x4],initial_M);
plot(x,M)
Error using odearguments (line 90)
@(X,M)S(X,M,GAMMA_B,A1VEC,B1VEC,XVEC) must return a column vector.

Error in ode45 (line 113) [neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ...

end

Answer 1

[Torsten]

The function must look like

function dMdx=s(x,M,gamma_b,a1Vec,b1Vec,xVec)
a1=interp1(xVec,a1Vec,x);
b1=interp1(xVec,b1Vec,x);
dMdx= M*((1+((gamma_b-1)/2)*M^2)/(1-M^2))*(-a1+((1+(gamma_b*M^2))/2)*b1);
end

Best wishes

Torsten.